1. Hydrophobic Mismatch between Helices and Lipid Bilayers
- Author
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J. Antoinette Killian, Huey W. Huang, Thomas M. Weiss, Roger E. Koeppe, and Patrick C.A. van der Wel
- Subjects
Circular dichroism ,Macromolecular Substances ,Membrane Fluidity ,Protein Conformation ,Lipid Bilayers ,Biophysics ,Molecular Conformation ,01 natural sciences ,Protein Structure, Secondary ,03 medical and health sciences ,Hydrophobic mismatch ,chemistry.chemical_compound ,X-Ray Diffraction ,0103 physical sciences ,Membrane fluidity ,Lipid bilayer ,030304 developmental biology ,0303 health sciences ,Membranes ,010304 chemical physics ,Bilayer ,Circular Dichroism ,technology, industry, and agriculture ,Lipid bilayer fusion ,Membrane Proteins ,Water ,Membranes, Artificial ,Crystallography ,chemistry ,Helix ,Liposomes ,Gramicidin ,Phosphatidylcholines ,lipids (amino acids, peptides, and proteins) ,Hydrophobic and Hydrophilic Interactions - Abstract
α-Helical transmembrane peptides, named WALP, with a hydrophobic sequence of leucine and alanine of varying length bordered at both ends by two tryptophans as membrane anchors, were synthesized to study the effect of hydrophobic matching in lipid bilayers. WALPs of 13-, 16-, and 19-residues were incorporated into 1,2-dilauroyl-sn-glycero-3-phosphocholine (12C), 1,2-tridecanoyl-sn-glycero-3-phosphocholine (13C), and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (14C) bilayers in the form of oriented multilayers. Oriented circular dichroism spectra and x-ray diffraction patterns showed that the peptides were homogenously distributed in the lipid bilayers with the helical axes oriented approximately normal to the plane of bilayers. But in all cases, x-ray diffraction showed that the peptides did not alter the thickness of the bilayer. This is contrary to the case of gramicidin where 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 1,2-dilauroyl-sn-glycero-3-phosphocholine clearly thinned and thickened, respectively, to approach the hydrophobic thickness of the gramicidin channels. The result seems to indicate that the packing of lipid chains around a single helix is fundamentally different from the way the chains pack against a large protein surface.
- Published
- 2003