Several new cross-strand interactions that stabilize hairpins and reduce end-fraying of such beta-sheet models have been developed. Chemical shift probes within these units can be used not only for measuring fold population changes but also the rates of folding and unfolding, from the exchange-broadening observed due to the folded/unfolded equilibrium. This method has allowed us to determine the effects of sequence and loop length on the rates of beta-strand association for a number of hairpin and beta-sheet models. These capping units have also been incorporated into reengineered versions of a WW-domain protein, with the earliest formed hairpin replaced by associated beta strands that are not connected by a reversing turn. Chemical shift deviations from coil norms for 13C=O and 13Cbeta sites in associated beta-strands provide excellent measures of fold populations and have revealed an unanticipated variation in backbone torsion angles in beta-hairpins and the edge strands of beta-sheets.

Models for evaluating hairpin formation dynamics and stability

243rd National Meeting (2012)

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