Mapping molecular flexibility of proteins with site-directed spin labeling: a case study of myoglobin.

ABSTRACT: Site-directed spin labeling (SDSL) has potential for mapping protein flexibility under physiological conditions. The purpose of the present study was to explore this potential using 38 singly spin-labeled mutants of myoglobin distributed throughout the sequence. Correlation of the EPR spectra with protein structure provides new evidence that the site-dependent variation in line shape, and hence motion of the spin label, is due largely to differences in mobility of the helical backbone in the ns time range. Fluctuations between conformational substates, typically in the μs-ms time range, are slow on the EPR time scale, and the spectra provide a snapshot of conformational equilibria frozen in time as revealed by multiple components in the spectra. A recent study showed that osmolyte perturba

SUBMITTER: Lopez CJ 

PROVIDER: S-EPMC3483079 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature