title: Freezing of dynamics of a methyl group in a protein hydrophobic core at cryogenic temperatures by deuteron NMR spectroscopy.
abstract: Methyl groups are thought to dominate the dynamics of proteins after slow collective modes of motion freeze out in a glass-transition process. In this work we investigate methyl group dynamics of a key hydrophobic core leucine residue in chicken villin headpiece subdomain protein at 140-4 K using deuteron NMR longitudinal relaxation measurements. A distinct increase in the apparent activation energy is observed at approximately 95 K, indicating an abrupt freezing of methyl group dynamics. Relaxation times at temperatures below 60 K are dominated by the deuteron tunneling mechanism.
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: Andrew S
authors.initials: AS
authors.lastname: Lipton
mesh_terms: D003080:Cold Temperature; D003903:Deuterium; D005615:Freezing; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D011506:Proteins / Q000737:chemistry*; D013696:Temperature
chemical_list: D011506:Proteins; D003903:Deuterium