Stephen H White

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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)
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)
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)
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)
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)
One of the ubiquitous features of membrane proteins is the preference of tryptophan and tyrosine residues for membrane surfaces that presumably arises from enhanced stability due to distinct interfacial interactions. The physical basis for this preference is widely believed to arise from amphipathic interactions related to imino group hydrogen bonding(More)
We show that the peptide backbone of an alpha-helix places a severe thermodynamic constraint on transmembrane (TM) stability. Neglect of this constraint by commonly used hydrophobicity scales underlies the notorious uncertainty of TM helix prediction by sliding-window hydropathy plots of membrane protein (MP) amino acid sequences. We find that an(More)
The reliability of the transmembrane (TM) sequence assignments for membrane proteins (MPs) in standard sequence databases is uncertain because the vast majority are based on hydropathy plots. A database of MPs with dependable assignments is necessary for developing new computational tools for the prediction of MP structure. We have therefore created MPtopo,(More)
Hydropathy plot methods form a cornerstone of membrane protein research, especially in the early stages of biochemical and structural characterization. Membrane Protein Explorer (MPEx), described in this article, is a refined and versatile hydropathy-plot software tool for analyzing membrane protein sequences. MPEx is highly interactive and facilitates the(More)
Lipids are produced, transported, and recognized by the concerted actions of numerous enzymes, binding proteins, and receptors. A comprehensive analysis of lipid molecules, "lipidomics," in the context of genomics and proteomics is crucial to understanding cellular physiology and pathology; consequently, lipid biology has become a major research target of(More)