Protein Folding Triggered by Electron Transfer

Abstract

Proteins do not fold by randomly searching a large number of nearly degenerate configurations; instead, an ensemble of unfolded molecules must traverse a complicated energy landscape to reach a thermodynamically stable structure. The fastest nuclear motions in proteins, rotations about single bonds, occur on the picosecond time scale and accompany both secondary- and tertiary-structure-forming processes. Short segments of secondary structure (e.g., α-helices) can be formed in nanoseconds, whereas the large-scale, collective motions associated with the development of tertiary structure fall in the microsecond to millisecond range. Misfolded structures or traps are frequently encountered in folding processes; escape from these traps (e.g., proline isomerization) can take seconds or even minutes. Understanding the key events in folding and identifying any partially folded intermediates are major goals of theoretical and experimental work.