Freezing of dynamics of a methyl group in a protein hydrophobic core at cryogenic temperatures by deuteron NMR spectroscopy.
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.
Vugmeyster
Liliya
L
University of Alaska--Anchorage, Anchorage, Alaska 99508, USA. aflv@uaa.alaska.edu
Ostrovsky
Dmitry
D
Ford
Joseph J
JJ
Lipton
Andrew S
AS
D003080:Cold Temperature; D003903:Deuterium; D005615:Freezing; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D011506:Proteins / Q000737:chemistry*; D013696:Temperature
D011506:Proteins; D003903:Deuterium