Effect of freezing conditions on distances and their distributions derived from Double Electron Electron Resonance (DEER): a study of doubly-spin-labeled T4 lysozyme.

ABSTRACT: Pulsed dipolar ESR spectroscopy, DEER and DQC, require frozen samples. An important issue in the biological application of this technique is how the freezing rate and concentration of cryoprotectant could possibly affect the conformation of biomacromolecule and/or spin-label. We studied in detail the effect of these experimental variables on the distance distributions obtained by DEER from a series of doubly spin-labeled T4 lysozyme mutants. We found that the rate of sample freezing affects mainly the ensemble of spin-label rotamers, but the distance maxima remain essentially unchanged. This suggests that proteins frozen in a regular manner in liquid nitrogen faithfully maintain the distance-dependent structural properties in solution. We compared the results from rapidly freeze-quenched (

SUBMITTER: Georgieva ER 

PROVIDER: S-EPMC3323113 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature