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Lipid dynamics in fast-tumbling bicelles with varying bilayer thickness: Effect of model transmembrane peptides
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
2008 (English)In: Biochimica et Biophysica Acta, ISSN 0006-3002, Vol. 1778, no 11, 2526-2534 p.Article in journal (Refereed) Published
Abstract [en]

The morphology of q=0.5 fast-tumbling bicelles prepared with three different acyl chain lengths has been investigated by NMR. It is shown that bicelles prepared with DLPC (12 C) and DHPC are on average larger than those containing DMPC or DPPC (14 and 16 C) and DHPC, which may be due to a higher degree of mixing between DLPC and DHPC. The fast internal mobility of the lipids was determined from natural abundance carbon-13 relaxation. A similar dynamical behaviour of the phospholipids in the three different bicelles was observed, although the DPPC lipid acyl chain displayed a somewhat lower degree of mobility, as evidenced by higher generalized order parameters throughout the acyl chain. Carbon-13 relaxation was also used to determine the effect of different model transmembrane peptides, with flanking Lys residues, on the lipid dynamics in the three different bicelles. All peptides had the effect of increasing the order parameters for the DLPC lipid, while no effect was observed on the longer lipid chains. This effect may be explained by a mismatch between the hydrophobic length of the peptides and the DLPC lipid acyl chain.

Place, publisher, year, edition, pages
2008. Vol. 1778, no 11, 2526-2534 p.
URN: urn:nbn:se:su:diva-14858ISI: 000261263500009PubMedID: 18692021OAI: diva2:181378
Available from: 2008-11-05 Created: 2008-11-05 Last updated: 2009-05-27Bibliographically approved
In thesis
1. Biophysical studies of membrane associated peptides
Open this publication in new window or tab >>Biophysical studies of membrane associated peptides
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A large part of the processes in living organisms involves proteins acting in a biological membrane. Biophysical studies on isolated model systems can give important understandings of the complicated biological mechanisms in the membrane. In this thesis peptide membrane interaction mechanisms are studied in several different systems. The membrane interactions of the unstructured endogenous opioid peptides dynorphinA (DynA) and dynorphinB (DynB) were investigated with Saturation Transfer Difference (STD) experiments, supplemented by various other NMR methods. The combined results support a conclusion that DynA binds to the lipid bilayer with the N-terminal residues inserted into the hydrophobic region and the C-terminal residues more loosely attached to the surface, while DynB is situated parallel to the bilayer. This difference in membrane interaction can explain observations that DynA has membrane perturbing effects while DynB has not. In the second study the binding domain of the glycosyltransferase A.laidlawii Monoglycosyldiacyl Glycerol Synthase (alMGS) was predicted and investigated mainly with NMR which enabled the determination of the 3D structure and position in a lipid environment. The phospholipid bilayers induce a large amphipathic α-helical content in the peptide, which aligns parallel but slightly tilted along the lipid surface with the N-terminus situated closer to the hydrophobic region. Lipid perturbation effects caused by peptide-membrane interactions were investigated by studying the influence of model transmembrane peptides on lipid dynamics in phospholipid bicelles with varying bilayer thickness. 13C-relaxation NMR of the lipids was used to survey the effects of the model peptides on the lipid bilayer.In paper IV and V structure and membrane interaction properties of the highly charged and flexible helix-turn-helix motif named the 'voltage sensor paddle' from two transmebrane voltage gated potassium channels was investigated. In membrane mimetic media, the KvaP paddle adopts the same type of helix-turn-helix conformation which can be seen in the Xray structure of the entire ion channel. The membrane interaction of the paddle HsapBK was compared with the corresponding one in KvaP, and both were inserted in the lipid bilayer but perturbed the lipid system differently, which may indicate differences in their function. Paper VI treats the structure of the novel site-specific fluorophore ReAsH bound to an optimized peptide sequence. The analysis shows that the important peptide mid segment configuration of CCPGCC is optimal for the ReAsH binding and that the N-terminal Phe1 plays an important role for the fluorophore process.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2009. 55 p.
NMR, spectroscopy, membrane interaction, bicelles
National Category
Chemical Sciences
Research subject
urn:nbn:se:su:diva-27488 (URN)978-91-7155-888-6 (ISBN)
Public defence
2009-06-04, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:00 (English)
Available from: 2009-05-14 Created: 2009-05-05 Last updated: 2012-08-28Bibliographically approved

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Lind, JesperMäler, Lena
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