March 31, 2010
Journal Article

Freezing of Dynamics of a Methyl Group in a Protein Hydrophobic Core at Cryogenic Temperatures by Deuteron NMR Spectroscopy

Abstract

Proteins undergo a number of changes when their temperature is dropped from the physiological range to much lower values. One of the most well-known dynamical changes undergone by proteins in a solid state is a so-called protein glass-transition, which is a dynamic transition occurring at about 200-230K leading to a loss of biological activity.1,2 X-ray diffraction, neutron scattering studies, and dielectric spectroscopy, as well as evidence from NMR relaxation measurements, indicate freezing of slow collective modes of motion below the glass transition temperature.3-8 Various arguments have been presented that connect the transition to solvent participation.1,4,8-10 In addition to the solvent-related modes that are frozen below the glass-transition temperature, there are anharmonic motions at temperatures below 200K which are likely to be dominated by methyl group dynamics down to about 100K.2,5,7 Recent neutron-scattering and NMR studies emphasize the role of these modes in low temperature dynamics. 2,5,7,11,12 One of the latest works on the subject by Bajaj et al.11 has reported a structural transition associated with dynamic processes in a solvent-free polypeptide. Thus, protein dynamics at low temperatures are complex and more studies are required to discern their pattern.

Revised: April 7, 2011 | Published: March 31, 2010

Citation

Vugmeyster L., D. Ostrovsky, J.J. Ford, and A.S. Lipton. 2010. Freezing of Dynamics of a Methyl Group in a Protein Hydrophobic Core at Cryogenic Temperatures by Deuteron NMR Spectroscopy. Journal of the American Chemical Society 132, no. 12:4038-4039. PNNL-SA-69606. doi:10.1021/ja909599k