title: Side-chain structure and dynamics at the lipid-protein interface: Val1 of the gramicidin A channel.
abstract: High resolution dynamics and structural information has been resolved from 2H solid-state NMR spectra of the Val-1 side-chain of the gramicidin channel in a lipid bilayer. Both powder pattern lineshapes and spectra from uniformly aligned samples of gramicidin in lipid bilayers have been analyzed to achieve a fully consistant interpretation of the data. Torsional motions about the C alpha C beta axis (chi 1) are shown to be three-state jumps in which the occupancy of the states is given by the ratio, 75:15:10 for the chi 1 angles of 184 degrees:304 degrees:64 degrees. The dominant conformer is also the most common conformation observed for valines in well defined protein structures. The distribution of conformational substates that represents the chi 1 dynamics appears to be largely independent of the lipid phase transition and the hydration of the sample. However, there is evidence that the residence time between jumps is dependent on the lipid phase transition. Although this time is shown to be approximately 1 microseconds below the phase transition temperature, it is in the fast exchange limit above the transition temperature.
authors.affiliation: Department of Chemistry, Florida State University, Tallahassee 32306.
authors.forename: K C
authors.initials: KC
authors.lastname: Lee
authors.forename: T A
authors.initials: TA
authors.lastname: Cross
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D055592:Biophysical Phenomena; D001703:Biophysics; D006096:Gramicidin / Q000737:chemistry*; D007473:Ion Channels / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011487:Protein Conformation; D013816:Thermodynamics; D014633:Valine / Q000737:chemistry
chemical_list: D007473:Ion Channels; D008051:Lipid Bilayers; D008563:Membrane Lipids; D008565:Membrane Proteins; D006096:Gramicidin; D014633:Valine