Protein dynamics studied by rotating frame 15N spin relaxation times
- Cite this article as:
- Szyperski, T., Luginbühl, P., Otting, G. et al. J Biomol NMR (1993) 3: 151. doi:10.1007/BF00178259
- 201 Downloads
Conformational rate processes in aqueous solutions of uniformly 15N-labeled pancreatic trypsin inhibitor (BPTI) at 36°C were investigated by measuring the rotating frame relaxation times of the backbone 15N spins as a function of the spin-lock power. Two different intramolecular exchange processes were identified. A first local rate process involved the residues Cys38 and Arg39, had a correlation time of about 1.3 ms, and was related to isomerization of the chirality of the disulfide bond Cys14-Cys38. A second, faster motional mode was superimposed on the disulfide bond isomerization and was tentatively attributed to local segmental motions in the polypeptide sequence-Cys14-Ala15-Lys16-. The correlation time for the overall rotational tumbling of the protein was found to be 2 ns, using the assumption that relaxation is dominated by dipolar coupling and chemical shift anistropy modulated by isotropic molecular reorientation.
KeywordsProtein dynamicsBasic pancreatic trypsin inhibitorNuclear magnetic resonance spectroscopyRotating frame spin relaxation times
basic pancreatic trypsin inhibitor
2D correlation spectroscopy
2D total correlation spectroscopy
time-proportional phase incrementation
chemical shift anisotropy
longitudinal relaxation time
transverse relaxation time
relaxation time in the rotating frame τ, correlation time for overall rotational reorientation of the protein
- τexs, τexf,
correlation times for two conformational exchange processes (slow and fast).