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  • 1. Aminlashgari, Nina
    et al.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hakkarainen, Minna
    Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry2011In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 3, no 1, p. 192-197Article in journal (Refereed)
    Abstract [en]

    The possibility to utilize nanocomposite films as easy-to-handle surfaces for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) of small molecules, such as pharmaceutical compounds, was evaluated. The signal-to-noise values of acebutolol, propranolol and carbamazepine obtained on the nanocomposite surfaces were higher than the values obtained on plain PLA surface showing that the nanoparticles participate in the ionization/desorption process even when they are immobilized in the polymer matrix. The advantages of nanocomposite films compared to the free nanoparticles used in earlier studies are the ease of handling and reduction of instrument contamination since the particles are immobilized into the polymer matrix. Eight inorganic nanoparticles, titanium dioxide, silicon dioxide, magnesium oxide, hydroxyapatite, montmorillonite nanoclay, halloysite nanoclay, silicon nitride and graphitized carbon black at different concentrations were solution casted to films with polylactide (PLA). There were large differences in signal intensities depending on the type of drug, type of nanoparticle and the concentration of nanoparticles. Polylactide with 10% titanium oxide or 10% silicon nitride functioned best as SALDI-MS surfaces. The limit of detection (LOD) for the study was ranging from 1.7 ppm up to 56.3 ppm and the signal to noise relative standard deviations for the surface containing 10% silicon nitride was approximately 20-30%. Scanning electron microscopy demonstrated in most cases a good distribution of the nanoparticles in the polymer matrix and contact angle measurements showed increasing hydrophobicity when the nanoparticle concentration was increased, which could influence the desorption and ionization. Overall, the results show that nanocomposite films have potential as surfaces for SALDI-MS analysis of small molecules.

  • 2. Andersson, Annika
    et al.
    Remnestål, Julia
    Nellgård, Bengt
    Vunk, Helian
    Kotol, David
    Edfors, Fredrik
    Uhlén, Mathias
    Schwenk, Jochen M.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zetterberg, Henrik
    Blennow, Kaj
    Månberg, Anna
    Nilsson, Peter
    Fredolini, Claudia
    Development of parallel reaction monitoring assays for cerebrospinal fluid proteins associated with Alzheimer's disease2019In: Clinica Chimica Acta, ISSN 0009-8981, E-ISSN 1873-3492, Vol. 494, p. 79-93Article in journal (Refereed)
    Abstract [en]

    Detailed knowledge of protein changes in cerebrospinal fluid (CSF) across healthy and diseased individuals would provide a better understanding of the onset and progression of neurodegenerative disorders. In this study, we selected 20 brain-enriched proteins previously identified in CSF by antibody suspension bead arrays (SBA) to be potentially biomarkers for Alzheimer's disease (AD) and verified these using an orthogonal approach. We examined the same set of 94 CSF samples from patients affected by AD (including preclinical and prodromal), mild cognitive impairment (MCI), non-AD dementia and healthy individuals, which had previously been analyzed by SBA. Twenty-eight parallel reaction monitoring (PRM) assays were developed and 13 of them could be validated for protein quantification. Antibody profiles were verified by PRM. For seven proteins, the antibody profiles were highly correlated with the PRM results (r > 0.7) and GAP43, VCAM1 and PSAP were identified as potential markers of preclinical AD. In conclusion, we demonstrate the usefulness of targeted mass spectrometry as a tool for the orthogonal verification of antibody profiling data, suggesting that these complementary methods can be successfully applied for comprehensive exploration of CSF protein levels in neurodegenerative disorders.

  • 3.
    Andrys, Rudolf
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Charles University Prague, Czech Republic .
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zguna, Nadezda
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Verschueren, Klaas
    De Borggraeve, Wim M.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Improved detection of beta-N-methylamino-L-alanine using N-hydroxysuccinimide ester of N-butylnicotinic acid for the localization of BMAA in blue mussels (Mytilus edulis)2015In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 13, p. 3743-3750Article in journal (Refereed)
    Abstract [en]

    beta-N-Methylamino-l-alanine (BMAA) is an important non-protein amino acid linked to neurodegenerative diseases, specifically amyotrophic lateral sclerosis (ALS). Because it can be transferred and bioaccumulated higher up the food chain, it poses significant public health concerns; thus, improved detection methods are of prime importance for the identification and management of these toxins. Here, we report the successful use of N-hydroxysuccinimide ester of N-butylnicotinic acid (C-4-NA-NHS) for the efficient separation of BMAA from its isomers and higher sensitivity in detecting BMAA compared to the current method of choice using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization. Implementation of this efficient method allowed localization of BMAA in the non-visceral tissues of blue mussels, suggesting that more efficient depuration may be required to remove this toxin prior to consumption. This is a crucial method in establishing the absence or presence of the neurotoxic amino acid BMAA in food, environmental or biomedical samples.

  • 4. Banack, Sandra Anne
    et al.
    Metcalf, James S.
    Jiang, Liying
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Craighead, Derek
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Cox, Paul Alan
    Cyanobacteria Produce N-(2-Aminoethyl)Glycine, a Backbone for Peptide Nucleic Acids Which May Have Been the First Genetic Molecules for Life on Earth2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 11, p. e49043-Article in journal (Refereed)
    Abstract [en]

    Prior to the evolution of DNA-based organisms on earth over 3.5 billion years ago it is hypothesized that RNA was the primary genetic molecule. Before RNA-based organisms arose, peptide nucleic acids may have been used to transmit genetic information by the earliest forms of life on earth. We discovered that cyanobacteria produce N-(2-aminoethyl)glycine (AEG), a backbone for peptide nucleic acids. We detected AEG in axenic strains of cyanobacteria with an average concentration of 1 µg/g. We also detected AEG in environmental samples of cyanobacteria as both a free or weakly bound molecule and a tightly bound form released by acid hydrolysis, at concentrations ranging from not detected to 34 µg/g. The production of AEG by diverse taxa of cyanobacteria suggests that AEG may be a primitive feature which arose early in the evolution of life on earth

  • 5. Bianchi, Federica
    et al.
    Agazzi, Silvia
    Riboni, Nicolò
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Parma, Italy.
    Erdal, Nejla
    Hakkarainen, Minna
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Anzillotti, Luca
    Andreoli, Roberta
    Moroni, Fabrizio
    Cecchi, Rossana
    Careri, Maria
    Novel sampling-substrates for the determination of new psychoactive substances in oral fluid by desorption electrospray ionization-high resolution mass spectrometryManuscript (preprint) (Other academic)
  • 6. Bianchi, Federica
    et al.
    Agazzi, Silvia
    Riboni, Nicolò
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Università di Parma, Italy.
    Erdal, Nejla
    Hakkarainen, Minna
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Anzillotti, Luca
    Andreoli, Roberta
    Marezza, Francesca
    Moroni, Fabrizio
    Cecchi, Rossana
    Careri, Maria
    Novel sample-substrates for the determination of new psychoactive substances in oral fluid by desorption electrospray ionization-high resolution mass spectrometry2019In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 202, p. 136-144Article, review/survey (Refereed)
    Abstract [en]

    A reliable screening and non invasive method based on the use of microextraction by packed sorbent coupled with desorption electrospray ionization-high resolution mass spectrometry was developed and validated for the detection of new psychoactive substances in oral fluid. The role of different sample substrates in enhancing signal intensity and stability was evaluated by testing the performances of two polylactide-based materials, i.e. non-functionalized and functionalized with carbon nanoparticles, and a silica-based material compared to commercially available polytetrafluorethylene supports. The best results were achieved by using the non-functionalized polylactide substrates to efficiently ionize compounds in positive ionization mode, whereas the silica coating proved to be the best choice for operating in negative ionization mode. LLOQs in the low mu g/L, a good precision with CV% always lower than 16% and RR% in the 83( +/- 4)-120( +/- 2)% range, proved the suitability of the developed method for the determination of the analytes in oral fluid. Finally, the method was applied for screening oral fluid samples for the presence of psychoactive substances during private parties, revealing mephedrone in only one sample out of 40 submitted to analysis.

  • 7. Bianchi, Federica
    et al.
    Riboni, Nicolò
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Parma, Italy.
    Termopoli, Veronica
    Mendez, Lucia
    Medina, Isabel
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Cappiello, Achille
    Careri, Maria
    MS-Based Analytical Techniques: Advances in Spray-Based Methods and EI-LC-MS Applications2018In: Journal of Analytical Methods in Chemistry, ISSN 2090-8865, E-ISSN 2090-8873, Vol. 2018, article id 1308167Article, review/survey (Refereed)
    Abstract [en]

    Mass spectrometry is the most powerful technique for the detection and identification of organic compounds. It can provide molecular weight information and a wealth of structural details that give a unique fingerprint for each analyte. Due to these characteristics, mass spectrometry-based analytical methods are showing an increasing interest in the scientific community, especially in food safety, environmental, and forensic investigation areas where the simultaneous detection of targeted and nontargeted compounds represents a key factor. In addition, safety risks can be identified at the early stage through online and real-time analytical methodologies. In this context, several efforts have been made to achieve analytical instrumentation able to perform real-time analysis in the native environment of samples and to generate highly informative spectra. (is review article provides a survey of some instrumental innovations and their applications with particular attention to spray-based MS methods and food analysis issues. The survey will attempt to cover the state of the art from 2012 up to 2017.

  • 8. Castiblanco, Gina A.
    et al.
    Rutishauser, Dorothea
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Martignon, Stefania
    Castellanos, Jaime E.
    Mejia, Wilson
    Identification of proteins from human permanent erupted enamel2015In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 123, no 6, p. 390-395Article in journal (Refereed)
    Abstract [en]

    Proteins from the extracellular matrix of enamel are highly specific and necessary for proper enamel formation. Most proteins are removed from the matrix by enamel proteases before complete mineralization is achieved; however, some residual protein fragments persist in the mineralized matrix of erupted enamel. So far, only amelogenin peptides obtained by traditional bottom-up proteomics have been recovered and identified in human permanent erupted enamel. In this study, we hypothesize that other enamel-specific proteins are also found in human permanent enamel, by analysing human erupted third molars. Pulverized enamel was used to extract proteins, and the protein extract was subjected directly to liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS) without a previous trypsin-digestion step. Amelogenin and non-amelogenin proteins (ameloblastin and enamelin) were succesfully identified. The sequences of the naturally occurring peptides of these proteins are reported, finding in particular that most of the peptides from the amelogenin X-isoform come from the tyrosine-rich amelogenin peptide (TRAP) and that some were identified in all specimens. In conclusion, our LC-MS/MS method without trypsin digestion increased the coverage of identification of the enamel proteome from a few amelogenin peptides to a higher number of peptides from three enamel-specific proteins.

  • 9. Douglas, T. A.
    et al.
    Tamburro, Davide
    Fredolini, C.
    Espina, B. H.
    Lepene, B. S.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Espina, V.
    Petricoin, E. F.
    Liotta, L. A.
    Luchini, A.
    The use of hydrogel microparticles to sequester and concentrate bacterial antigens in a urine test for Lyme disease2011In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, no 4, p. 1157-1166Article in journal (Refereed)
    Abstract [en]

    Hydrogel biomarker capturing microparticles were evaluated as a biomaterial to amplify the sensitivity of urine testing for infectious disease proteins. Lyme disease is a bacterial infection transmitted by ticks. Early diagnosis and prompt treatment of Lyme disease reduces complications including arthritis and cardiac involvement. While a urine test is highly desirable for Lyme disease screening, this has been difficult to accomplish because the antigen is present at extremely low concentrations, below the detection limit of clinical immunoassays. N-isopropylacrylamide (NIPAm) - acrylic acid (AAc) microparticles were covalently functionalized with amine containing dyes via arnidation of carboxylic groups present in the microparticles. The dyes act as affinity baits towards protein analytes in solution. NIPAm/AAc microparticles functionalized with acid black 48 (AB48) mixed with human urine, achieved close to one hundred percent capture and 100 percent extraction yield of the target antigen. In urine, microparticles sequestered and concentrated Lyme disease antigens 100 fold, compared to the absence of microparticles, achieving an immunoassay detection sensitivity of 700 pg/mL in 10 mL urine. Antigen present in a single infected tick could be readily detected following microparticle sequestration. Hydrogel microparticles functionalized with high affinity baits can dramatically increase the sensitivity of urinary antigen tests for infectious diseases such as Lyme disease. These findings justify controlled clinical studies evaluating the sensitivity and precision of Lyme antigen testing in urine.

  • 10. Duitama, Sandra M.
    et al.
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Cordoba, Diana
    Duran, Paola
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mejia, Wilson
    Soy protein supplement intake for 12 months has no effect on sexual maturation and may improve nutritional status in pre-pubertal children2018In: Journal of Paediatrics and Child Health, ISSN 1034-4810, E-ISSN 1440-1754, Vol. 54, no 9, p. 997-1004Article in journal (Refereed)
    Abstract [en]

    Aim: To evaluate the intake of a soy protein-based supplement (SPS) and its effects on the sexual maturation and nutritional status of prepubertal children who consumed it for a year.

    Methods: Healthy children (n = 51) were recruited and randomly assigned to consume the lunch fruit juice with (n = 29) or without (n = 22) addition of 45 g of a commercial soy protein-based supplement (SPS) over 12 months. Nutritional assessment including anthropometry (bodyweight, height, triceps skinfold thickness, mid-upper arm circumference), body mass index (BMI), upper arm muscle area, arm muscle circumference, upper arm area, upper arm fat area data were derived from measures using usual procedures; age and gender-specific percentiles were used as reference. Sexual maturation was measured by Tanner stage. Isoflavones were quantified using liquid chromatography and tandem mass spectrometry.

    Results: Height, BMI/age, weight/age and height/age were significantly different (P < 0.05) at 12 months between girls in the control and intervention groups. Statistically significant differences between groups by gender (P < 0.05) were found in boys in the control group for the triceps skinfold thickness and fat area. Nutritional status was adequate according to the World Health Organization parameters. On average, 0.130 mg/kg body weight/day of isoflavones were consumed by children, which did not show significant differences in their sexual maturation.

    Conclusion: Consumption of SPS for 12 months did not affect sexual maturation or the onset of puberty in prepubertal boys and girls; however, it may have induced an increase in height, BMI/age, height/age and weight/age of the girls, associated with variations in fat-free mass.

  • 11. Faassen, Elisabeth J.
    et al.
    Antoniou, Maria G.
    Beekman-Lukassen, Wendy
    Blahova, Lucie
    Chernova, Ekaterina
    Christophoridis, Christophoros
    Combes, Audrey
    Edwards, Christine
    Fastner, Jutta
    Harmsen, Joop
    Hiskia, Anastasia
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Kaloudis, Triantafyllos
    Lopicic, Srdjan
    Lürling, Miquel
    Mazur-Marzec, Hanna
    Meriluoto, Jussi
    Porojan, Cristina
    Viner-Mozzini, Yehudit
    Zguna, Nadezda
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A Collaborative Evaluation of LC-MS/MS Based Methods for BMAA Analysis: Soluble Bound BMAA Found to Be an Important Fraction2016In: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 14, no 3, article id 45Article in journal (Refereed)
    Abstract [en]

    Exposure to beta-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D(3)BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D(3)BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery (<10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis.

  • 12.
    Gao, Qiuju
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Monosaccharide compositional analysis of marine polysaccharides by hydrophilic interaction liquid chromatography-tandem mass spectrometry2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 399, no 7, p. 2517-2529Article in journal (Refereed)
    Abstract [en]

    A simple and sensitive method was developed using hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry for determination of monosaccharides liberated from marine polysaccharides by acidic hydrolysis. Optimal separation of diastereomeric monosaccharides including hexoses, pentoses, and deoxyhexoses was achieved using an aminopropyl bonded column with mobile phase containing ternary solvents (acetonitrile/methanol/water) in conjunction with MS/MS in SRM mode. Mechanisms for fragmentation of deprotonated monosaccharides with regard to cross-ring cleavage were proposed. Matrix effects from coeluting interferences were observed and isotopic-labeled internal standard was used to compensate for the signal suppression. The method demonstrated excellent instrumental limits of detection (LOD), ranging from 0.7 to 4.2 pg. Method LODs range from 0.9 to 5.1 nM. The proposed method was applied to the analysis of polysaccharides in seawater collected from the open leads of the central Arctic Ocean in the summer of 2008.

  • 13.
    Hessle, Viktoria
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Björk, Petra
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Sokolowski, Marcus
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Gonzalez de Valdivia, Ernesto
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Silverstein, Rebecca
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Artemenko, Konstantin
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Tyagi, Anu
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Maddalo, Gianluca
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Helbig, Roger
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    Zubarev, Roman A
    Visa, Neus
    Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
    The exosome Associates Cotranscriptionally with the Nascent Pre-mRNP through Interactions with Heterogeneous Nuclear Ribonucleoproteins2009In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 20, no 15, p. 3459-3470Article in journal (Refereed)
    Abstract [en]

    Eukaryotic cells have evolved quality control mechanisms to degrade aberrant mRNA molecules and prevent the synthesis of defective proteins that could be deleterious for the cell. The exosome, a protein complex with ribonuclease activity, is a key player in quality control. An early quality checkpoint takes place cotranscriptionally but little is known about the molecular mechanisms by which the exosome is recruited to the transcribed genes. Here we study the core exosome subunit Rrp4 in two insect model systems, Chironomus and Drosophila. We show that a significant fraction of Rrp4 is associated with the nascent pre-mRNPs and that a specific mRNA-binding protein, Hrp59/hnRNP M, interacts in vivo with multiple exosome subunits. Depletion of Hrp59 by RNA interference reduces the levels of Rrp4 at transcription sites, which suggests that Hrp59 is needed for the exosome to stably interact with nascent pre-mRNPs. Our results lead to a revised mechanistic model for cotranscriptional quality control in which the exosome is constantly recruited to newly synthesized RNAs through direct interactions with specific hnRNP proteins.

  • 14.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Aigret, Benoit
    De Borggraeve, Wim M.
    Spacil, Zdenek
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Selective LC-MS/MS method for the identification of BMAA from its isomers in biological samples2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 403, no 6, p. 1719-1730Article in journal (Refereed)
    Abstract [en]

    Algal blooms are well-known sources of acute toxic agents that can be lethal to aquatic organisms. However, one such toxin, beta--methylamino--alanine (BMAA) is also believed to cause amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. The detection and identification of BMAA in natural samples were challenging until the recent introduction of reliable methods. However, the issue of potential interference from unknown isomers of BMAA present in samples has not yet been thoroughly investigated. Based on a systematic database search, we generated a list of all theoretical BMAA structural isomers, which was subsequently narrowed down to seven possible interfering compounds for further consideration. The seven possible candidates satisfied the requirements of chemical stability and also shared important structural domains with BMAA. Two of the candidates, 2,4-diaminobutyric acid (DAB) and -(2-aminoethyl) glycine (AEG) have recently been studied in the context of BMAA. A further isomer, beta-amino--methyl-alanine (BAMA), has to be considered because it can potentially yield the fragment ion, which is diagnostic for BMAA. Here, we report the synthesis and analysis of BAMA, together with AEG, DAB, and other isomers that are of interest in the separation and detection of BMAA in biological samples by using either high-performance liquid chromatography or ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. We detected for the first time BAMA in blue mussel and oyster samples. This work extends the previously developed liquid chromatography-tandem mass spectrometry platform Spacil et al. (Analyst 135:127, 2010) to allow BMAA isomers to be distinguished, improving the detection and identification of this important amino acid.

  • 15.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Spacil, Zdenek
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. University of Washington, USA.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nilsson, Lennart
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Cordova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid-Sweden University, Sweden.
    Abiotic synthesis of amino acids and self-crystallization under prebiotic conditions2014In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, article id 6769Article in journal (Refereed)
    Abstract [en]

    Building on previous research on the origin and homochirality of life, this study focuses on analyses profiling important building blocks of life: the natural amino acids. The spark discharge variation of the iconic Miller experiment was performed with a reducing gas mixture of ammonia, methane, water and hydrogen. Amino acid analysis using liquid chromatography coupled with tandem mass spectrometry after pre-column derivatizaiton revealed the generation of several amino acids including those essential for life. Re-crystallization of the synthetic products and enantiomeric ratio analysis were subsequently performed. Results from liquid chromatography coupled with either fluorescent detector or tandem mass spectrometry after pre-column derivatization with chiral reagent revealed spontaneous and effective asymmetric resolution of serine and alanine. This work describes a useful analytical platform for investigation of hypotheses regarding the origin and homochirality of amino acids under prebiotic conditions. The formation of numerous amino acids in the electric discharge experiment and the occurrence of high enantiomeric ratios of amino acids in re-crystallization experiment give valuable implications for future studies in unraveling fundamental questions regarding origins and evolution of life.

  • 16.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Lage, Sandra
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jonasson, Sara
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Shams, Shiva
    Mehine, Martin
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Diatoms: A Novel Source for the Neurotoxin BMAA in Aquatic Environments2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 1, article id e84578Article in journal (Refereed)
    Abstract [en]

    Amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease is a neurological disorder linked to environmental exposure to a non-protein amino acid, beta-N-methylamino-L-alanine (BMAA). The only organisms reported to be BMAA-producing, are cyanobacteria - prokaryotic organisms. In this study, we demonstrate that diatoms - eukaryotic organisms - also produce BMAA. Ultra-high-performance liquid chromatography coupled with tandem mass spectrometry revealed the occurrence of BMAA in six investigated axenic diatom cultures. BMAA was also detected in planktonic field samples collected on the Swedish west coast that display an overrepresentation of diatoms relative to cyanobacteria. Given the ubiquity of diatoms in aquatic environments and their central role as primary producers and the main food items of zooplankton, the use of filter and suspension feeders as livestock fodder dramatically increases the risk of human exposure to BMAA-contaminated food.

  • 17.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Detection of endogenous BMAA in dinoflagellate (Heterocapsa triquetra) hints at evolutionary conservation and environmental concern2014In: PubRaw Science, ISSN 2313-1128, Vol. 1, no 2, p. 1-8Article in journal (Refereed)
  • 18.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Johnston, Eric
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åberg, K. Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Strategy for quantifying trace levels of BMAA in cyanobacteria by LC/MS/MS2013In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 405, no 4, p. 1283-1292Article in journal (Refereed)
    Abstract [en]

    The cyanobacterial neurotoxin β-N-methylamino--alanine (BMAA) is an amino acid that is putatively associated with the pathology of amyotrophic lateral sclerosis/Parkinsonism –dementia complex (ALS-PDC) disease. It raises serious health risk concerns since cyanobacteria are ubiquitous thus making human exposure almost inevitable. The identification and quantification of BMAA in cyanobacteria is challenging because it is present only in trace amounts and occurs alongside structurally similar compounds such as BMAA isomers. This work describes an enhanced liquid chromatography/tandem mass spectrometry platform that can distinguish BMAA from its isomers β-amino-N-methyl-alanine, N-(2-oethyl) glycine (AEG), and 2,4-diaminobutyric acid, thus ensuring confident identification of BMAA. The method's sensitivity was improved fourfold by a post-column addition of acetonitrile. The instrument and method limits of detection were shown to be 4.2 fmol/injection (or 0.5 g/one column) and 0.1 μg/g dry weight of cyanobacteria, respectively. The quantification method uses synthesized deuterated BMAA as an internal standard and exhibits good linearity, accuracy, and precision. Matrix effects were also investigated, revealing an ion enhancement of around 18 %. A lab-cultured cyanobacterial sample (Leptolyngbya PCC73110) was analyzed and shown to contain about 0.73 μg/g dry weight BMAA. The isomer AEG, whose chromatographic properties closely resemble those of BMAA, was also detected. These results highlight the importance of distinguishing BMAA from its isomers for reliable identification as well as providing a sensitive and accurate quantification method for measuring trace levels of BMAA in cyanobacterial samples.

  • 19.
    Jiang, Liying
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Kiselova, Nadezda
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Rosén, Johan
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Quantification of neurotoxin BMAA (beta-N-methylamino-L-alanine) in seafood from Swedish markets2014In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, article id 6931Article in journal (Refereed)
    Abstract [en]

    The neurotoxin beta-N-methylamino-L-alanine (BMAA) produced naturally by cyanobacteria, diatoms and dinoflagellates can be transferred and accumulated up the food chain, and may be a risk factor for neurodegenerative diseases. This study provides the first systematic screening of BMAA exposure of a large population through the consumption of seafood sold in metropolitan markets. BMAA was distinguished from known isomers by liquid chromatography tandem mass spectrometry after acidic hydrolysis and derivatization. Using deuterium-labeled internal standard, BMAA was quantified as 0.01-0.90 mu g/g wet weight of tissues in blue mussel, oyster, shrimp, plaice, char and herring, but was undetectable (<0.01 mu g/g) in other samples (salmon, cod, perch and crayfish). Provided that the content of BMAA detected is relevant for intake calculations, the data presented may be used for a first estimation of BMAA exposure through seafood from Swedish markets, and to refine the design of future toxicological experiments and assessments.

  • 20.
    Jonasson, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Berntzon, Lotta
    Stockholm University, Faculty of Science, Department of Botany.
    Spacil, Zdenek
    Stockholm University, Faculty of Science, Department of Analytical Chemistry. Charles University Prague, Czech Republic .
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ronnevi, Lars-Olof
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Transfer of a cyanobacterial neurotoxin within a temperate aquatic ecosystem suggests pathways for human exposure2010In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 20, p. 9252-9257Article in journal (Refereed)
    Abstract [en]

    beta-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid produced by most cyanobacteria, has been proposed to be the causative agent of devastating neurodegenerative diseases on the island of Guam in the Pacific Ocean. Because cyanobacteria are widespread globally, we hypothesized that BMAA might occur and bioaccumulate in other ecosystems. Here we demonstrate, based on a recently developed extraction and HPLC-MS/MS method and long-term monitoring of BMAA in cyanobacterial populations of a temperate aquatic ecosystem (Baltic Sea, 2007-2008), that BMAA is biosynthesized by cyanobacterial genera dominating the massive surface blooms of this water body. BMAA also was found at higher concentrations in organisms of higher trophic levels that directly or indirectly feed on cyanobacteria, such as zooplankton and various vertebrates (fish) and invertebrates (mussels, oysters). Pelagic and benthic fish species used for human consumption were included. The highest BMAA levels were detected in the muscle and brain of bottom-dwelling fishes. The discovery of regular biosynthesis of the neurotoxin BMAA in a large temperate aquatic ecosystem combined with its possible transfer and bioaccumulation within major food webs, some ending in human consumption, is alarming and requires attention.

  • 21. Kaldmae, Margit
    et al.
    Österlund, Nicklas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lianoudaki, Danai
    Sahin, Cagla
    Bergman, Peter
    Nyman, Tomas
    Kronqvist, Nina
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Allison, Timothy M.
    Marklund, Erik G.
    Landreh, Michael
    Gas-Phase Collisions with Trimethylamine-N-Oxide Enable Activation-Controlled Protein Ion Charge Reduction2019In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 30, no 8, p. 1385-1388Article in journal (Refereed)
    Abstract [en]

    Modulating protein ion charge is a useful tool for the study of protein folding and interactions by electrospray ionization mass spectrometry. Here, we investigate activation-dependent charge reduction of protein ions with the chemical chaperone trimethylamine-N-oxide (TMAO). Based on experiments carried out on proteins ranging from 4.5 to 35kDa, we find that when combined with collisional activation, TMAO removes approximately 60% of the charges acquired under native conditions. Ion mobility measurements furthermore show that TMAO-mediated charge reduction produces the same end charge state and arrival time distributions for native-like and denatured protein ions. Our results suggest that gas-phase collisions between the protein ions and TMAO result in proton transfer, in line with previous findings for dimethyl- and trimethylamine. By adjusting the energy of the collisions experienced by the ions, it is possible to control the degree of charge reduction, making TMAO a highly dynamic charge reducer that opens new avenues for manipulating protein charge states in ESI-MS and for investigating the relationship between protein charge and conformation.

  • 22.
    Karlsson, Isabella
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Samuelsson, Kristin
    Ponting, David J.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Peptide Reactivity of Isothiocyanates - Implications for Skin Allergy2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 21203Article in journal (Refereed)
    Abstract [en]

    Skin allergy is a chronic condition that affects about 20% of the population of the western world. This disease is caused by small reactive compounds, haptens, able to penetrate into the epidermis and modify endogenous proteins, thereby triggering an immunogenic reaction. Phenyl isothiocyanate (PITC) and ethyl isothiocyanate (EITC) have been suggested to be responsible for allergic skin reactions to chloroprene rubber, the main constituent of wetsuits, orthopedic braces, and many types of sports gear. In the present work we have studied the reactivity of the isothiocyanates PITC, EITC, and tetramethylrhodamine-6-isothiocyanate (6-TRITC) toward peptides under aqueous conditions at physiological pH to gain information about the types of immunogenic complexes these compounds may form in the skin. We found that all three compounds reacted quickly with cysteine moieties. For PITC and 6-TRITC the cysteine adducts decomposed over time, while stable adducts with lysine were formed. These experimental findings were verified by DFT calculations. Our results may suggest that the latter are responsible for allergic reactions to isothiocyanates. The initial adduct formation with cysteine residues may still be of great importance as it prevents hydrolysis and facilitates the transport of isothiocyanates into epidermis where they can form stable immunogenic complexes with lysine-containing proteins.

  • 23.
    Karlsson, Isabella
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Samuelsson, Kristin
    Simonsson, Carl
    Stenfeldt, Anna-Lena
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jonsson, Charlotte
    Karlberg, Ann-Therese
    The Fate of a Hapten - From the Skin to Modification of Macrophage Migration Inhibitory Factor (MIF) in Lymph Nodes2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 2895Article in journal (Refereed)
    Abstract [en]

    Skin (contact) allergy, the most prevalent form of immunotoxicity in humans, is caused by low molecular weight chemicals (haptens) that penetrate stratum corneum and modify endogenous proteins. The fate of haptens after cutaneous absorption, especially what protein(s) they react with, is largely unknown. In this study the fluorescent hapten tetramethylrhodamine isothiocyanate (TRITC) was used to identify hapten-protein conjugates in the local lymph nodes after topical application, as they play a key role in activation of the adaptive immune system. TRITC interacted with dendritic cells but also with T and B cells in the lymph nodes as shown by flow cytometry. Identification of the most abundant TRITC-modified protein in lymph nodes by tandem mass spectrometry revealed TRITC-modification of the N-terminal proline of macrophage migration inhibitory factor (MIF) - an evolutionary well-conserved protein involved in cell-mediated immunity and inflammation. This is the first time a hapten-modified protein has been identified in lymph nodes after topical administration of the hapten. Most haptens are electrophiles and can therefore modify the N-terminal proline of MIF, which has an unusually reactive amino group under physiological conditions; thus, modification of MIF by haptens may have an immunomodulating role in contact allergy as well as in other immunotoxicity reactions.

  • 24. Karlsson, Oskar
    et al.
    Jiang, Liying
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Andersson, Marie
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Brittebo, Eva B.
    Protein association of the neurotoxin and non-protein amino acid BMAA (beta-N-methylamino-L-alanine) in the liver and brain following neonatal administration in rats2014In: Toxicology Letters, ISSN 0378-4274, E-ISSN 1879-3169, Vol. 226, no 1, p. 1-5Article in journal (Refereed)
    Abstract [en]

    The environmental neurotoxin beta-N-methylamino-L-alanine (BMAA) is not an amino acid that is normally found in proteins. Our previous autoradiographic study of H-3-labeled BMAA in adult mice unexpectedly revealed a tissue distribution similar to that of protein amino acids. The aim of this study was to characterize the distribution of free and protein-bound BMAA in neonatal rat tissues following a short exposure using autoradiographic imaging and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The autoradiographic imaging of C-14-L-BMAA demonstrated a distinct uptake of radioactivity that was retained following acid extraction in tissues with a high rate of cell turnover and/or protein synthesis. The UHPLC-MS/MS analysis conclusively demonstrated a dose-dependent increase of protein-associated BMAA in neonatal rat tissues. The level of protein-associated BMAA in the liver was more than 10 times higher than that in brain regions not fully protected by the blood-brain barrier which may be due to the higher rate of protein synthesis in the liver. In conclusion, this study demonstrated that BMAA was associated with rat proteins suggesting that BMAA may be mis-incorporated into proteins. However, protein-associated BMAA seemed to be cleared over time, as none of the samples from adult rats had any detectable free or protein-associated BMAA.

  • 25. Karlsson, Oskar
    et al.
    Jiang, Liying
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ersson, Lisa
    Malmström, Tim
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Brittebo, Eva B.
    Environmental neurotoxin interaction with proteins: Dose-dependent increase of free and protein-associated BMAA (beta-N-methylamino-L-alanine) in neonatal rat brain2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 15570Article in journal (Refereed)
    Abstract [en]

    beta-Methylamino-L-alanine (BMAA) is implicated in the aetiology of neurodegenerative disorders. Neonatal exposure to BMAA induces cognitive impairments and progressive neurodegenerative changes including intracellular fibril formation in the hippocampus of adult rats. It is unclear why the neonatal hippocampus is especially vulnerable and the critical cellular perturbations preceding BMAA-induced toxicity remains to be elucidated. The aim of this study was to compare the level of free and protein-associated BMAA in neonatal rat brain and peripheral tissues after different exposures to BMAA. Ultra-high performance liquid chromatography-tandem mass spectrometry analysis revealed that BMAA passed the neonatal blood-brain barrier and was distributed to all studied brain areas. BMAA was also associated to proteins in the brain, especially in the hippocampus. The level in the brain was, however, considerably lower compared to the liver that is not a target organ for BMAA. In contrast to the liver there was a significantly increased level of protein-association of BMAA in the hippocampus and other brain areas following repeated administration suggesting that the degradation of BMAA-associated proteins may be lower in neonatal brain than in the liver. Additional evidence is needed in support of a role for protein misincorporation in the neonatal hippocampus for long-term effects of BMAA.

  • 26.
    Kärkäs, Markus D.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Karlsson, Erik A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lee, Bao-Lin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Shariatgorji, Mohammadreza
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hansson, Örjan
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Light-Induced Water Oxidation by a Ru-complex Containing a Bio-Inspired Ligand2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 28, p. 7953-7959Article in journal (Refereed)
    Abstract [en]

    The new Ru-complex 8 containing the bio-inspired ligand 7 was successfully synthesized and characterized. Complex 8 could efficiently catalyze water oxidation using CeIV and RuIII as chemical oxidants. More importantly, this complex has sufficiently low overpotential to utilize ruthenium polypyridyl-type complexes as photosensitizers.

  • 27.
    Leonova, Ekaterina
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Solid-state NMR investigations of Si-29 and N-15 enriched silicon nitride2009In: Solid State Nuclear Magnetic Resonance, ISSN 0926-2040, E-ISSN 1527-3326, Vol. 36, no 1, p. 11-18Article in journal (Refereed)
  • 28.
    Maddalo, Gianluca
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Chovanec, Peter
    Stenberg-Bruzell, Filippa
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Nielsen, Hailyn V
    Jensen-Seaman, Michael
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Kline, Kimberly
    Daley, Daniel
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    A reference map of the membrane proteome of Enterococcus faecalis2011In: Proteomics, ISSN 1615-9853, E-ISSN 1615-9861, Vol. 11, no Special issue, p. 3935-3941Article in journal (Refereed)
    Abstract [en]

    Enterococcus faecalis is a gram-positive bacterium that is part of the indigenous microbiotica of humans and animals as well as an opportunistic pathogen. In this study, we have fractionated the membrane proteome of E. faecalis and identified many of its constituents by mass spectrometry. We present blue native-/SDS-PAGE reference maps that contain 102 proteins. These proteins are important for cellular homeostasis, virulence, and antibiotic intervention. Intriguingly, many proteins with no known function were also identified, indicating that there are substantial gaps in the knowledge of this organism's biology. On a more limited scale, we also provide insight into the composition of membrane protein complexes. This study is a first step toward elucidating the membrane proteome of E. faecalis, which is critical for a better understanding of how this bacterium interacts with a host and with the extracellular milieu.

  • 29.
    Maddalo, Gianluca
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Proteomic platform for the analysis of inner and outer membrane proteomes in Escherichia coli2009Conference paper (Other academic)
  • 30.
    Maddalo, Gianluca
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Adams, Christopher M.
    Fung, Eva
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Zubarev, Roman A.
    Sedzik, Jan
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Porcine P2 myelin protein primary structure and bound fatty acids determined by mass spectrometry2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 397, no 5, p. 1903-1910Article in journal (Refereed)
    Abstract [en]

    Complementary collision-induced/electron capture dissociation Fourier-transform ion cyclotron resonance mass spectrometry was used to fully sequence the protein P2 myelin basic protein. It is an antigenic fatty-acid-binding protein that can induce experimental autoimmune neuritis: an animal model of Guillain-Barre syndrome, a disorder similar in etiology to multiple sclerosis. Neither the primary structure of the porcine variant, nor the fatty acids bound by the protein have been well established to date. A 1.8-angstrom crystal structure shows but a bound ligand could not be unequivocally identified. A protocol for ligand extraction from protein crystals has been developed with subsequent gas chromatography MS analysis allowing determination that oleic, stearic, and palmitic fatty acids are associated with the protein. The results provide unique and general evidence of the utility of mass spectrometry for characterizing proteins from natural sources and generating biochemical information that may facilitate attempts to elucidate the causes for disorders such as demyelination.

  • 31.
    Maddalo, Gianluca
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Stenberg-Bruzell, Filippa
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Götzke, Hansjörg
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Toddo, Stephen
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Patrik, Björkholm
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Eriksson, Hanna
    Chovanec, Peter
    Genevaux, Pierre
    Lehtiö, Janne
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Daley, Daniel O.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Systematic Analysis of Native Membrane Protein Complexes in Escherichia coli2011In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 10, no 4, p. 1848-1859Article in journal (Refereed)
    Abstract [en]

    The cell envelope of Escherichia coli is an essential structure that modulates exchanges between the cell and the extra-cellular milieu. Previous proteomic analyses have suggested that it contains a significant number of proteins with no annotated function. To gain insight into these proteins and the general organization of the cell envelope proteome, we have carried out a systematic analysis of native membrane protein complexes. We have identified 30 membrane protein complexes (6 of which are novel) and present reference maps that can be used for cell envelope profiling. In one instance, we identified a protein with no annotated function (YfgM) in a complex with a well-characterized periplasmic chaperone (PpiD). Using the guilt by association principle, we suggest that YfgM is also part of the periplasmic chaperone network. The approach we present circumvents the need for engineering of tags and protein overexpression. It is applicable for the analysis of membrane protein complexes in any organism and will be particularly useful for less-characterized organisms where conventional strategies that require protein engineering (i.e., 2-hybrid based approaches and TAP-tagging) are not feasible.

  • 32.
    Mashayekhy Rad, Farshid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Investigation of ultrahigh-performance liquid chromatography/travelling-wave ion mobility/time-of-flight mass spectrometry for fast profiling of fatty acids in the high Arctic sea surface microlayer2018In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 32, no 12, p. 942-950Article in journal (Refereed)
    Abstract [en]

    Rationale

    Fatty acids are enriched in the ocean surface microlayer (SML) and have as a consequence been detected worldwide in sea spray aerosols. In searching for a relationship between the properties of the atmospheric aerosol and its ability to form cloud condensation nuclei and to promote cloud droplet formation over remote marine areas, the role of surface active fatty acids sourced from the SML is of interest to be investigated. Here is presented a fast method for profiling of major fatty acids in SML samples collected in the high Arctic (89 °N, 1 °W) in the summer of 2001.

    Methods

    UHPLC/travelling‐wave ion mobility spectrometry (TWIMS)/time‐of‐flight (TOF) mass spectrometry (MS) for profiling was evaluated and compared with UHPLC/TOFMS. No sample preparation, except evaporation and centrifugation, was necessary to perform prior to the analysis.

    Results

    TOFMS data on accurate mass, isotopic ratios and fragmentation patterns enabled identification of the fatty acids. The TWIMS dimension added to the selectivity by extensive reduction of the noise level and the entire UHPLC/TWIMS/TOFMS method provided a fast profiling of the acids, ranging from C8 to C24. Hexadecanoic and octadecanoic acids were shown to yield the highest signals among the fatty acids detected in a high Arctic SML sample, followed by the unsaturated octadecenoic and octadecadienoic acids. The predominance of signal from even‐numbered carbon chains indicates a mainly biogenic origin of the detected fatty acids.

    Conclusions

    This study presents a fast alternative method for screening and profiling of fatty acids, which has the advantage of not requiring any complicated sample preparation thus limiting the loss of analytes. Almost no manual handling, together with the very small sample volumes needed, is certainly beneficial for the determination of trace amounts and should open up the field of applications to also include atmospheric aerosol and fog.

  • 33.
    Mashayekhy Rad, Farshid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Department of Meteorology .
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gilles, Philippe
    Rutgeerts, Laurens A. J.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Measurements of Atmospheric Proteinaceous Aerosol in the Arctic Using a Selective UHPLC/ESI-MS/MS Strategy2019In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 30, no 1, p. 161-173Article in journal (Refereed)
    Abstract [en]

    In this article, an analytical methodology to investigate the proteinaceous content in atmospheric size-resolved aerosols collected at the Zeppelin observatory (79 °N, 12 °E) at Ny Ålesund, Svalbard, from September to December 2015, is proposed. Quantitative determination was performed after acidic hydrolysis using ultrahigh-performance liquid chromatography in reversed-phase mode coupled to electrospray ionization tandem mass spectrometry. Chromatographic separation, as well as specificity in the identification, was achieved by derivatization of the amino acids with N-butyl nicotinic acid N-hydroxysuccinimide ester prior to the analysis. The chromatographic run was performed within 11 min and instrumental levels of detection (LODs) were between 0.2 and 8.1 pg injected on the column, except for arginine which exhibited an LOD of 37 pg. Corresponding method LODs were between 0.01 and 1.9 fmol/m3, based on the average air sampling volume of 57 m3. The sum of free amino acids and hydrolyzed polyamino acids was shown to vary within 6–2914 and 0.02–1417 pmol/m3 for particles in sizes < 2 and 2–10 μm in equivalent aerodynamic diameter, respectively. Leucine, alanine, and valine were the most abundant among the amino acids in both aerosol size fractions. In an attempt to elucidate source areas of the collected aerosols, 5- to 10-day 3D backward trajectories reaching the sampling station were calculated. Overall, the method described here provides a first time estimate of the proteinaceous content, that is, the sum of free and polyamino acids, in size-resolved aerosols collected in the Arctic.

  • 34.
    Mozuraitis, Raimondas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Murtazina, Rushana
    Zurita, Javier
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Pei, Yuxin
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Borg-Karlson, Anna Karin
    Anti-aphrodisiac pheromone, a renewable signal in adult butterfliesManuscript (preprint) (Other academic)
  • 35.
    Pisareva, Tatiana
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Shumskaya, Maria
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Maddalo, Gianluca
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Norling, Birgitta
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Proteomics of Synechocystis sp. PCC 6803 Identification of novel integral plasma membrane proteins: Identification of novel integral plasma membrane proteins2007In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 274, no 3, p. 791-804Article in journal (Refereed)
    Abstract [en]

    The cyanobacterial plasma membrane is an essential cell barrier with functions such as the control of taxis, nutrient uptake and secretion. These functions are carried out by integral membrane proteins, which are difficult to identify using standard proteomic methods. In this study, integral proteins were enriched from purified plasma membranes of Synechocystis sp. PCC 6803 using urea wash followed by protein resolution in 1D SDS/PAGE. In total, 51 proteins were identified by peptide mass fingerprinting using MALDI-TOF MS. More than half of the proteins were predicted to be integral with 1–12 transmembrane helices. The majority of the proteins had not been identified previously, and include members of metalloproteases, chemotaxis proteins, secretion proteins, as well as type 2 NAD(P)H dehydrogenase and glycosyltransferase. The obtained results serve as a useful reference for further investigations of the address codes for targeting of integral membrane proteins in cyanobacteria.

  • 36.
    Quaranta, Alessandro
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Spasova, Maya
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Passarini, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Karlsson, Isabella
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ndreu, Lorena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Thorsén, Gunnar
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    N-glycosylation profiling of selected intact proteins by high-resolution mass spectrometry (MS) and glycan analysis using ion mobility-MS/MSManuscript (preprint) (Other academic)
    Abstract [en]

    Glycosylation influences structure and functionality of glycoproteins, and is regulated by genetic and environmental factors. Types and abundances of glycans on glycoproteins can vary due to diseases like cancer, inflammation, autoimmune and neurodegenerative disorders. Due to the crucial role of glycans in modulating protein function, glycosylation analysis is of prime importance in glycoprotein biopharmaceuticals quality control. We present a method for identification and quantification of glycoforms directly on intact proteins after immunoaffinity purification from biological fluids. The method was validated and applied to serum transferrin and to the biopharmaceutical trastuzumab. The accuracy ranged from 2.1 to 7.9%, and intra- and inter-day precision were 3.1 and 8.2%. Sensitivity and linearity were suitable for serum analysis and LOQs were calculated to be 3.1 (transferrin) and 4.4 (trastuzumab) µg/mL. Application to transferrin from five healthy serum samples yielded concentrations in agreement with blood reference levels (1.95-3.11 mg/mL). The structures of the identified glycans were assigned by ion mobility spectrometry coupled to tandem mass spectrometry. No chromatographic separation was required, and sample preparation was performed in a semi-automatic way, reducing the analysis time to 1-3 minutes. Hence, this method could be suitable for clinical laboratories and for quality control on large batches of biopharmaceuticals.

  • 37.
    Redeby, Theres
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Altamore, Timothy A.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ambrosi, Annalisa
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Broo, Kerstein
    Borje, Anna
    Karlberg, Ann-Therese
    Specific Adducts Formed through a Radical Reaction between Peptides and Contact Allergenic Hydroperoxides2010In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 23, no 1, p. 203-210Article in journal (Refereed)
    Abstract [en]

    The first step in the development of contact allergy (allergic contact dermatitis) includes the penetration of an allergy-causing chemical (hapten) into the skin, where it binds to macromolecules such as proteins. The protein-hapten adduct is then recognized by the immune system as foreign to the body. For hydroperoxides, no relevant hapten target proteins or protein-hapten adducts have so far been identified. In this work, bovine insulin and human angiotensin I were used as model peptides to investigate the haptenation mechanism of three hydroperoxide haptens: (5R)-5-isopropenyl-2-methyl-2-cyclohexene-1-hydroperoxide (Lim-2-OOH), cumene hydroperoxide (CumOOH), and 1-(1-hydroperoxy-1-methylethyl) cyclohexene (CycHexOOH). These hydroperoxides are expected to react via a radical mechanism, for which 5,10,15,20-tetraphenyl-21H,23H-porphine iron(III) chloride (Fe(III)TPPCl) was used as a radical initiator. The reactions were carried out in 1:1 ethanol/10 mM amonium acetate buffer pH 7.4, for 3 h at 37 T, and the reaction products were either enzymatically digested or analyzed directly by MALDI/TOF-MS, HPLC/MS/MS, and 2D gel electrophoresis. Both hydroperoxide-specific and unspecific reaction products were detected, but only it) the presence of the iron catalyst. In the absence of catalyst, the hydroperoxides remained unreacted. This suggests that the hydroperoxides call enter into the skin and remain inert until activated. Through the detection of a Lim-2-OOH adduct bound at the first histidine (of two) of angiotensin I, it was confirmed that hydroperoxides have the potential to form specific antigens in contact allergy.

  • 38.
    Riboni, Nicolò
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Parma, Italy.
    Quaranta, Alessandro
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Motwani, Hitesh
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Österlund, Nicklas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bianchi, Federica
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Solvent-Assisted Paper Spray Ionization (SAPSI) for the Analysis of Biomolecules and BiofluidsManuscript (preprint) (Other academic)
  • 39.
    Riboni, Nicoló
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Parma, Italy.
    Quaranta, Alessandro
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Motwani, Hitesh
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Österlund, Nickles
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bianchi, Federica
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Solvent-Assisted Paper Spray Ionization Mass Spectrometry (SAPSI-MS) for the Analysis of Biomolecules and Biofluids2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 10296Article in journal (Refereed)
    Abstract [en]

    Paper Spray Ionization (PSI) is commonly applied for the analysis of small molecules, including drugs, metabolites, and pesticides in biological fluids, due to its high versatility, simplicity, and low costs. In this study, a new setup called Solvent Assisted Paper Spray Ionization (SAPSI), able to increase data acquisition time, signal stability, and repeatability, is proposed to overcome common PSI drawbacks. The setup relies on an integrated solution to provide ionization potential and constant solvent flow to the paper tip. Specifically, the ion source was connected to the instrument fluidics along with the voltage supply systems, ensuring a close control over the ionization conditions. SAPSI was successfully applied for the analysis of different classes of biomolecules: amyloidogenic peptides, proteins, and N-glycans. The prolonged analysis time allowed real-time monitoring of processes taking places on the paper tip, such as amyloid peptides aggregation and disaggregation phenomena. The enhanced signal stability allowed to discriminate protein species characterized by different post translational modifications and adducts with electrophilic compounds, both in aqueous solutions and in biofluids, such as serum and cerebrospinal fluid, without any sample pretreatment. In the next future, application to clinical relevant modifications, could lead to the development of quick and cost-effective diagnostic tools.

  • 40.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Amini, Nahid
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Silicon nitride nanoparticles for surface-assisted laser desorption/ionization of small molecules2009In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 11, no 6, p. 1509-1512Article in journal (Refereed)
    Abstract [en]

    Conventional matrix-assisted laser desorption/ionization mass spectrometry is limited to analyses of higher molecular weight compounds due to high background noise generated by the matrix in the lower mass region. Surface-assisted laser desorption/ionization (SALDI) mass spectrometry is an alternative solution to this problem. Nanoparticles, structured silicon surfaces and carbon allotropes are commonly used as SALDI surfaces. Here, for the first time, we demonstrate the application of silicon nitride nanoparticles as a suitable medium for laser desorption/ionization of small drug molecules.

  • 41.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Amini, Nahid
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Thorsen, Gunnar
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Crescenzi, Carlo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    µ-trap for the SALDI-MS screening of organic compounds prior to LC/MS analysis2008In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 80, no 14, p. 5515-5523Article in journal (Refereed)
    Abstract [en]

    A procedure for rapidly screening and quantitatively analyzing organic molecules is presented, in which a miniaturized solid-phase extraction (SPE) cartridge containing 0.6 mg of graphitized carbon black (the GCB-mu-trap) is used for sample pretreatment. Then surface-assisted laser desorption ionization dine-of-flight mass spectrometry (SALDI-TOF-MS) screening is followed by liquid chromatography/mass spectrometry (LC/MS) for robust quantitative analysis of samples containing analytes of interest. Liquid samples with volumes up to 100 mL were extracted using the GCB-mu-trap, and SALDI screening was performed by transferring a few particles of the GCB 4 sorbent from the mu-trap onto a stainless steel plate. Analytes were then simply ionized and desorbed by irradiating the GCB 4 particles without any further pretreatment. GCB 4 was found to be an excellent surface for the SALDI analysis of small molecules, providing spectra with very clean backgrounds. The small size of the cartridge (micropipet filter tip) results in enrichment of the analytes on a small surface area, affording low SALDI-TOF-MS detection limits. Furthermore, the removal of just a few particles from the p-trap does not significantly affect the subsequent quantitative determination. This approach offers considerable reductions in analytical costs by eliminating unnecessary SPE-LC/MS analyses.

  • 42.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Astorga-Wells, J
    Jornvall, H
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Microfluidic electrocapture-assisted mass spectrometry of membrane-associated polypeptides2008In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 80, p. 7116-7120Article in journal (Refereed)
  • 43.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Astorga-Wells, Juan
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Trends in the bioanalytical applications of microfluidic electrocapture2011In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 399, no 1, p. 191-195Article in journal (Refereed)
    Abstract [en]

    Downscaled analytical tools for sample preparation have offered benefits such as higher throughput, easier automation and lower sample/reagent consumption. Microfluidic electrocapture, which is a newly developed sample preparation/manipulation system, uses an electric field to trap and separate charged species without using any solid sorbent. The feasibility of using microfluidic electrocapture is reported for separation, clean-up, concentration, microreactions and complexation studies of proteins, peptides and other biologically important biomolecules. The instrumentation and applications of microfluidic electrocapture are reviewed and an overview is provided of future perspectives offered by the current and envisaged platforms.

  • 44.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Spacil, Zdenek
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Maddalo, Gianluca
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Cardenas, Lourdes B.
    Plant Biology Division, Institute of Biological Sciences, University of the Philippines Los Banos, College, Laguna 4031, The Philippines.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Matrix-free thin-layer chromatography/laser desorption ionization mass spectrometry for facile separation andidentification of medicinal alkaloids2009In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 23, no 23, p. 3655-3660Article in journal (Refereed)
    Abstract [en]

    Quaternary protoberberine alkaloids belong to a pharmaceutically important class of isoquinoline alkaloids associated with bactericidal, fungicidal, insecticidal and antiviral activities. As traditional medicine gains wider acceptance, quick and robust analytical methods for the screening and analysis of plants containing these compounds attract considerable interest. Thin-layer chromatography (TLC) combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful technique but suffers from dilution of the TLC bands resulting in decreased sensitivity and masking of signals in the low-mass region both due to addition of matrix. This study integrates for the first time conventional silica gel TLC and laser desorption ionization mass spectrometry (LDI-MS) thus eliminating the need for any external matrix. Successful separation of berberine (Rf = 0.56) and palmatine (Rf = 0.46) from Berberis barandana including their identification by MS are demonstrated. Furthermore, a robust electrospray ionization (ESI)-MS method utilizing residual sample from TLC for quantification of berberine applying selected reaction monitoring and standard addition method is presented. The amount of berberine in the plant root prepared for the study was determined to be 0.70% (w/w). Copyright © 2009 John Wiley & Sons, Ltd.

  • 45. Sharon, M
    et al.
    Ilag, L
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Robinson, C.V
    Evidence for Micellar Structure in the Gas Phase2007In: J Am Chem Soc, Vol. 129, p. 8740-6Article in journal (Refereed)
  • 46.
    Sigurlásdóttir, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Engman, Jakob
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Eriksson, Olaspers Sara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Saroj, Sunil D.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Zguna, Nadezda
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lloris-Garcerá, Pilar
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jonsson, Ann-Beth
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Host cell-derived lactate functions as an effector molecule in Neisseria meningitidis microcolony dispersal2017In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 13, no 4, article id e1006251Article in journal (Refereed)
    Abstract [en]

    The development of meningococcal disease, caused by the human pathogen Neisseria meningitidis, is preceded by the colonization of the epithelial layer in the nasopharynx. After initial adhesion to host cells meningococci form aggregates, through pilus-pilus interactions, termed microcolonies from which the bacteria later detach. Dispersal from microcolonies enables access to new colonization sites and facilitates the crossing of the cell barrier; however, this process is poorly understood. In this study, we used live-cell imaging to investigate the process of N. meningitidis microcolony dispersal. We show that direct contact with host cells is not required for microcolony dispersal, instead accumulation of a host-derived effector molecule induces microcolony dispersal. By using a host-cell free approach, we demonstrated that lactate, secreted from host cells, initiate rapid dispersal of microcolonies. Interestingly, metabolic utilization of lactate by the bacteria was not required for induction of dispersal, suggesting that lactate plays a role as a signaling molecule. Furthermore, Neisseria gonorrhoeae microcolony dispersal could also be induced by lactate. These findings reveal a role of host-secreted lactate in microcolony dispersal and virulence of pathogenic Neisseria.

  • 47.
    Spacil, Z
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, J
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    LC-MS/MS identification of -N-methylamino-L-alanine in Cyanobacteria Chromatography and Tandem Mass Spectrometry2009Conference paper (Other academic)
  • 48.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, J
    Jonasson, S
    Bergman, B
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Identification of -N-methylamino-L-alanine (BMAA) in Cyanobacteria2009In: Abstracts / 12th EuCheMS International conference on chemistry and the environment: 14-17 June 2009, Stockholm university, Stockholm, Sweden, 2009Conference paper (Other academic)
  • 49.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Jonasson, Sara
    Stockholm University, Faculty of Science, Department of Botany.
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Analytical protocol for identification of BMAA and DAB in biologicalsamples2010In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 135, p. 127-132Article in journal (Refereed)
    Abstract [en]

     

    b

    -N-methylamino-L-alanine (BMAA) is a non-protein amino acid, thought to be inflicting neurodegenerative diseases related to ALS/PDC in human beings. Due to conflicting data concerning the presence of BMAA in various biological matrixes, we present a robust and sensitive method for high confidence identification of BMAA after derivatization by 6-aminoquinolyl-N

    -hydroxysuccinimidyl carbamate (AQC). The efficient sample pretreatment in combination with LC-MS/MS SRM enables chromatographic separation of BMAA from the isomer 2,3-diaminobutyric acid (DAB). The method is applicable for selective BMAA/DAB detection in various biological samples ranging from a prokaryotic cyanobacterium to eukaryotic fish.

  • 50.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Amini, Nahid
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Solich, Petr
    Department of Analytical Chemistry, Faculty of Pharmacy, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Matrix-less laser desorption/ionisation mass spectrometry of polyphenols in red wine2009In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 23, no 12, p. 1834-1840Article in journal (Refereed)
    Abstract [en]

    Matrix-assisted laser desorption/ionisation (MALDI) of small molecules is challenging and in most cases impossible due to interferences from matrix ions precluding analysis of molecules <300-500 Da. A common matrix such as ferulic acid belongs to an important class of compounds associated with antioxidant activity. If the shared phenolic structure is related to the propensity as an active MALDI matrix then it follows that direct laser desorption/ionisation should be possible for polyphenols. Indeed matrix-less laser desorption/ionisation mass spectrometry is achieved whereby the analyte functions as a matrix and was used to monitor low molecular weight compounds in wine samples. Sensitivity ranging from 0.12-87 pmol/spot was achieved for eight phenolic acids (4-coumaric, 4-hydroxybenzoic, caffeic, ferulic, gallic, protocatechuic, syringic, vanillic) and 0.02 pmol/spot for trans-resveratrol. Additionally, 4-coumaric, 4-hydroxybenzoic, caffeic, ferulic, gallic, syringic, vanillic acids and trans-resveratrol were identified in wine samples using accurate mass measurements consistent with reported profiles based on liquid chromatography (LC)/MS. Minimal sample pre-treatment make the technique potentially appropriate for fingerprinting, screening and quality control of wine samples. Copyright © 2009 John Wiley & Sons, Ltd.

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