Mapping backbone and side-chain interactions in the transition state of a coupled protein folding and binding reaction.

ABSTRACT: Understanding the mechanism of protein folding requires a detailed knowledge of the structural properties of the barriers separating unfolded from native conformations. The S-peptide from ribonuclease S forms its α-helical structure only upon binding to the folded S-protein. We characterized the transition state for this binding-induced folding reaction at high resolution by determining the effect of site-specific backbone thioxylation and side-chain modifications on the kinetics and thermodynamics of the reaction, which allows us to monitor formation of backbone hydrogen bonds and side-chain interactions in the transition state. The experiments reveal that α-helical structure in the S-peptide is absent in the transition state of binding. Recognition between the unfolded S-peptide and the

SUBMITTER: Bachmann A 

PROVIDER: S-EPMC3054012 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature