title: Probing the dynamics of a protein hydrophobic core by deuteron solid-state nuclear magnetic resonance spectroscopy.
abstract: With the goal of investigating dynamical features of hydrophobic cores of proteins over a wide range of temperatures, the chicken villin headpiece subdomain protein (HP36) was labeled at a "single" site corresponding to any one of the two C(delta)D(3) groups of leucine-69, which is located in a key position of the core. The main techniques employed are deuteron NMR quadrupolar echo line shape analysis, and T(1Z) (Zeeman) and T(1Q) (quadrupolar order) relaxation experiments performed at 11.7 and 17.6 T over the temperature range of 112 to 298 K. The experimental data are compared with computer simulations. The deuteron line shapes give an excellent fit to a three-mode motional model that consists of (a) fast three-site rotational jumps about the pseudo C(3) methyl spinning axis, (b) slower reorientation of the spinning axis, described by diffusion along a restricted arc, and (c) large angle jumps between traces of rotameric conformers. Relaxation behavior is described by a phenomenological distribution of activation energies for three-site hops at high temperatures that collapses to a single, distinctly smaller value for lower temperatures.
authors.affiliation: University of Alaska-Anchorage, Anchorage, Alaska 99508, USA. aflv@uaa.alaska.edu
authors.forename: Liliya
authors.initials: L
authors.lastname: Vugmeyster
authors.forename: Dmitry
authors.initials: D
authors.lastname: Ostrovsky
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Ford
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Burton
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Lipton
authors.forename: Gina L
authors.initials: GL
authors.lastname: Hoatson
authors.forename: Robert L
authors.initials: RL
authors.lastname: Vold
mesh_terms: D000818:Animals; D002645:Chickens; D003198:Computer Simulation; D003903:Deuterium / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007930:Leucine / Q000737:chemistry; D008956:Models, Chemical; D016900:Neurofilament Proteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010446:Peptide Fragments / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D016900:Neurofilament Proteins; D010446:Peptide Fragments; C115223:villin headpiece subdomain peptide; D003903:Deuterium; D007930:Leucine