The influence of intramolecular bridges on the dynamics of a protein folding reaction

Jody M. Mason, Nicholas Gibbs, Richard B. Sessions, Anthony R. Clarke

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Thirteen versions of a β-sheet protein have been constructed, each with a single, surface-exposed disulfide bridge. A comparison of folding kinetics, in oxidizing and reducing conditions, is used to elucidate the order in which β-strands become associated during the folding process and, hence, the relationship between topology and folding dynamics. In common with the wild-type molecule, all the proteins fold through a two-step (three state) mechanism with a rapidly formed intermediate which slowly converts to the native state. In a majority of cases, the bridge is seen to stabilize the folded state, and for five of the modified proteins, the additional stability is greater than 3 kcal/mol. Surprisingly, cross-links which connect β-strands which are distant in sequence predominantly stabilize the rapidly formed intermediate state, suggesting that these strand−strand interactions occur in the initial stages of folding. Cross-links which stabilize local hairpins have their major influence on the second, rate-determining step leading to significant enhancements in the folding rate. We find that enhancement of the folding rate in the second, rate-limiting step is correlated with a reduction in contact order in the same way as in naturally occurring proteins of different folds. The large increases in native-state stability resulting from the insertion of disulfide bridges on the surface of β-sheet structures have implications for enhancing the robustness of proteins by molecular engineering.
Original languageEnglish
Pages (from-to)12093-12099
JournalBiochemistry
Volume41
Issue number40
Early online date11 Sep 2002
DOIs
Publication statusPublished - 1 Oct 2002

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