Monday, 23 May 2005
397

This presentation is part of: Spectroscopy of Biomolecules Posters

Ultrafast Folding of Trp-cage Mutants

Michelle R. DeRitter, Xi Yang, Jeffrey Saven, and Feng Gai. University of Pennsylvania, Philadelphia, PA

Owing to its small size and simple structure, the mini-protein Trp-cage is an excellent model system for protein folding studies. Herein, we investigated the thermal stability and folding kinetics of a series of Trp-cage mutants, designed based on a statistic computational method, by static infrared (IR) and circular dichroism (CD) spectroscopies and IR temperature jump (T-jump) method. Our results support a folding mechanism wherein the formation of the salt-bridge between Arg-16 and Asp-9 is not rate-limiting, in disagreement with a recent theoretical study. Moreover, we found that mutant P12W exhibits not only an enhanced thermal stability but also a faster folding rate, indicating that the hydrophobic interaction plays an important role in the stabilization of both the native and transition states. In addition, our results highlight the usefulness of the stabilizing Trp-Trp interaction in protein design.

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