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Fragmentation of Amino Acids and Microsolvated Peptides and Nucleotides using Electrospray Ionization Tandem Mass Spectrometry
Stockholm University, Faculty of Science, Department of Physics. (Molecular Physics)
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents three different series of high energy (keV) collision experiments as well as a brief scientific introduction to the field. In the first series, protonated glycine and leucine were collided with carbon dioxide and a beam attenuation method was applied to determine their total fragmentation cross sections. A technique was also presented for how to restore the resolution in mass spectra obtained with a hemispherical electrostatic analyzer followed by a position sensitive detector (micro-channel plate equipped with a resistive anode). In the second series of experiments, Collision Induced Dissociation (CID) and Electron Capture Induced Dissociation (ECID) studies were performed on the nucleotide adenosine 5'-monophosphate anion (AMP-) in water complexes.  The two dissociation techniques revealed different fragmentation patterns and a numerical solvent evaporation model was used to interpret the spectra. It was then found that the CID and ECID processes were associated with different internal energy distributions. The third experiment concerned ECID of the protonated dipeptide glycine-alanine ([GA+H]+) in complexes with water, methanol, acetonitrile or crown ether. Depending on the attached molecular species, different ratios between the two competing channels ammonia loss and N-Cα bond cleavage were observed. Quantum chemical calculations revealed that a notable shift in the location of the captured electron occurred for the case of two acetonitriles and one crown ether compared to the bare ion and the ion in complexes with either water or methanol. Finally, this thesis will discuss developments of the electrospray ionization platform as well as the new Double ElectroStatic IonRing ExpEriment (DESIREE) facility.

Place, publisher, year, edition, pages
2010. , 80 p.
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-37202OAI: oai:DiVA.org:su-37202DiVA: diva2:294406
Presentation
2010-02-15, FA31, Albanova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:15 (English)
Opponent
Supervisors
Available from: 2011-02-18 Created: 2010-02-17 Last updated: 2011-02-18Bibliographically approved
List of papers
1. DESIREE as a new tool for interstellar ion chemistry
Open this publication in new window or tab >>DESIREE as a new tool for interstellar ion chemistry
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2008 (English)In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 7, no 3-4, 205-208 p.Article in journal (Refereed) Published
Abstract [en]

A novel cryogenic electrostatic storage device consisting of two ion-beam storage rings with a common straight section for studies of interactions between oppositely charged ions at low and well-defined relative velocities is under construction at Stockholm University. Here we consider the prospect of using this new tool to measure cross-sections and rate coefficients for mutual neutralization reactions of importance in interstellar ion chemistry in general and specifically in cosmic pre-biotic ion chemistry.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-32615 (URN)10.1017/S1473550408004229 (DOI)000273383100003 ()
Available from: 2009-12-15 Created: 2009-12-14 Last updated: 2017-12-12Bibliographically approved
2. Collisions with biomolecules embedded in smallwater clusters
Open this publication in new window or tab >>Collisions with biomolecules embedded in smallwater clusters
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2009 (English)Conference paper, Published paper (Refereed)
Abstract [en]

We have studied fragmentation of water embedded adenosine 5’-monophosphate(AMP) anions after collisions with neutral sodium atoms. At a collision energy of 50 keV,loss of water molecules from the collisionally excited cluster ions is the dominant process andfragmentation of the AMP itself is almost completely prohibited if the number of attachedwater molecules is larger than 13. However, regardless of the initial number of water moleculesattached to the ion, capture of an electron, i.e. formation of a dianion, always leads to loss ofa single hydrogen atom accompanied by evaporation of water molecules. This damaging effectbecomes more important as the size of the water cluster increases, which is just the oppositeto the protective behavior observed for collision induced dissociation (CID) without electrontransfer. For both cases, the loss of water molecules within the experimental time frame isqualitatively well described by means of a common model of an evaporative ensemble. Thesesimulations, however, indicate that characteristically different distributions of internal energyare involved in CID and electron capture induced dissociation.

Series
Journal of Physics: Conference Series, ISSN 1742-6596 ; 194
National Category
Atom and Molecular Physics and Optics Physical Sciences
Research subject
Biophysics; Physics
Identifiers
urn:nbn:se:su:diva-34740 (URN)10.1088/1742-6596/194/1/012053 (DOI)
Conference
XXVI International Conference on Photonic, Electronic and Atomic Collisions
Available from: 2010-01-11 Created: 2010-01-11 Last updated: 2011-10-27Bibliographically approved
3. Electron capture induced dissociation of nucleotide anions in water nanodroplets
Open this publication in new window or tab >>Electron capture induced dissociation of nucleotide anions in water nanodroplets
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2008 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, no 7, 075102- p.Article in journal (Refereed) Published
Abstract [en]

We have studied the outcome of collisions between the hydrated nucleotide anion adenosine 5′-monophosphate (AMP) and sodium. Electron capture leads to hydrogen loss as well as water evaporation regardless of the initial number m of water molecules attached to the parent ion (m ⩽ 16). The yield of dianions with microsecond lifetimes increases strongly with m, which is explained from dielectric screening of the two charges by the water nanodroplet. For comparison, collision induced dissociation results in water losses with no or very little damage of the AMP molecule itself.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-17045 (URN)10.1063/1.2839597 (DOI)000253336800043 ()18298174 (PubMedID)
Available from: 2009-01-05 Created: 2009-01-05 Last updated: 2017-12-13Bibliographically approved
4. Electron-Capture-Induced Dissociation of Microsolvated Di- and > Tripeptide Monocations: Elucidation of Fragmentation Channels from > Measurements of Negative Ions
Open this publication in new window or tab >>Electron-Capture-Induced Dissociation of Microsolvated Di- and > Tripeptide Monocations: Elucidation of Fragmentation Channels from > Measurements of Negative Ions
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2009 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 10, no 9-10, 1619-1623 p.Article in journal (Refereed) Published
Abstract [en]

The branching ratio between ammonia loss and NCα bond cleavage of singly charged microsolvated peptides after electron capture from cesium depends on the solvent molecule attached. Density functional calculations reveal that for [GA+H]+(CE) (G=glycine, A=alanine, CE=crown ether), the singly occupied molecular orbital of the neutral radical is located mainly on the amide group (see picture).

The results from an experimental study of bare and microsolvated peptide monocations in high-energy collisions with cesium vapor are reported. Neutral radicals form after electron capture from cesium, which decay by H loss, NH3 loss, or NCα bond cleavage into characteristic z. and c fragments. The neutral fragments are converted into negatively charged species in a second collision with cesium and are identified by means of mass spectrometry. For protonated GA (G=glycine, A=alanine), the branching ratio between NH3 loss and NCα bond cleavage is found to strongly depend on the molecule attached (H2O, CH3CN, CH3OH, and 18-crown-6 ether (CE)). Addition of H2O and CH3OH increases this ratio whereas CH3CN and CE decrease it. For protonated AAA ([AAA+H]+), a similar effect is observed with methanol, while the ratio between the z1 and z2 fragment peaks remains unchanged for the bare and microsolvated species. Density functional theory calculations reveal that in the case of [GA+H]+(CE), the singly occupied molecular orbital is located mainly on the amide group in accordance with the experimental results.

Keyword
cations, electron transfer, excited states, mass spectrometry, peptides
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-33290 (URN)10.1002/cphc.200800782 (DOI)000267928100039 ()
Available from: 2009-12-22 Created: 2009-12-22 Last updated: 2017-12-12Bibliographically approved

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