title: Rapidly-frozen polypeptide samples for characterization of high definition dynamics by solid-state NMR spectroscopy.
abstract: A method is described for defining anisotropic local dynamics in polypeptides by solid-state NMR. To avoid conformational heterogeneity introduced by large hexagonal ice crystals in low temperature hydrated samples, a fast-freezing technique is used for sample preparation. For a demonstration of this approach, the backbone librational motions of the gramicidin A channel conformation are studied in hydrated DMPC bilayers. The static 15N chemical shift tensor is characterized at 123 K for the Ala3 site. The temperature dependence of this tensor yields a determination of the librational amplitude and anisotropy of the motionally sampled space. This amplitude represents the sum of nanosecond and picosecond time-frame motions, both of which have a significant amplitude.
authors.affiliation: Department of Chemistry, Florida State University, Tallahassee 32306-3006.
authors.forename: N D
authors.initials: ND
authors.lastname: Lazo
authors.forename: W
authors.initials: W
authors.lastname: Hu
authors.forename: K C
authors.initials: KC
authors.lastname: Lee
authors.forename: T A
authors.initials: TA
authors.lastname: Cross
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D005615:Freezing; D006096:Gramicidin / Q000737:chemistry*; D007053:Ice; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics
chemical_list: D007053:Ice; D010455:Peptides; D006096:Gramicidin; D000409:Alanine