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Membrane proteins depend on complex translocation machineries for insertion into target membranes. Although it has long been known that an abundance of nonpolar residues in transmembrane helices is the principal criterion for membrane insertion, the specific sequence-coding for transmembrane helices has not been identified. By challenging the endoplasmic(More)
Stably folded membrane proteins reside in a free energy minimum determined by the interactions of the peptide chains with each other, the lipid bilayer hydrocarbon core, the bilayer interface, and with water. The prediction of three-dimensional structure from sequence requires a detailed understanding of these interactions. Progress toward this objective is(More)
We present in this paper the complete structure of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) in the L alpha phase (66% RH, 23 degrees C) obtained by the joint refinement of neutron and x-ray lamellar diffraction data. The structural details obtained have previously required a large number of neutron diffraction experiments, using numerous(More)
The partitioning of membrane-active oligopeptides into membrane interfaces promotes the formation of secondary structure. A quantitative description of the coupling of structure formation to partitioning, which may provide a basis for understanding membrane protein folding and insertion, requires an appropriate free energy scale for partitioning. A complete(More)
Octanol-to-water solvation free energies of acetyl amino amides (Ac-X-amides) [Fauchère, J.L., & Pliska, V. (1983) Eur. J. Med. Chem. --Chim. Ther. 18,369] form the basis for computational comparisons of protein stabilities by means of the atomic solvation parameter formalism of Eisenberg and McLachlan [(1986) Nature 319, 199]. In order to explore this(More)
Membranes have a potent ability to promote secondary structure formation in a wide range of membrane-active peptides, believed to be due to a reduction through hydrogen bonding of the energetic cost of partitioning peptide bonds. This process is of fundamental importance for understanding the mechanism of action of toxins and antimicrobial peptides and the(More)
The mechanism of voltage gating in K+ channels is controversial. The paddle model posits that highly charged voltage-sensor domains move relatively freely across the lipid bilayer in response to membrane depolarization; competing models picture the charged S4 voltage-sensor helix as being shielded from lipid contact by other parts of the protein. We(More)
Tryptophan fluorescence is a powerful tool for studying protein structure and function, especially membrane-active proteins and peptides. It is arguably the most frequently used tool for examining the interactions of proteins and peptides with vesicular unilamellar model membranes. However, high light scattering associated with vesicular membrane systems(More)
Melittin is arguably the most widely studied amphipathic, membrane-lytic alpha-helical peptide. Although several lines of evidence suggest an interfacial membrane location at low concentrations, melittin's exact position and depth of penetration into the hydrocarbon core are unknown. Furthermore, the structural basis for its lytic action remains largely a(More)
This is the first in a series of papers concerned with methods for the determination of the structures of fluid phospholipid bilayers in the liquid-crystalline (L alpha) phase. The basic approach is the joint refinement of quasimolecular models (King and White, 1986. Biophys. J. 49:1047-1054) using x-ray and neutron diffraction data. We present here (a) the(More)