(581d) Dynamic Surface Activity by Folding and Unfolding a Helical Peptide

Transient folding of proteins is a common natural phenomenon that facilitates the protein's ability to bind targets with unparalleled specificity and time scales on the order of seconds in environments full of similar targets. This process is not possible with the classic static ?lock-and-key' perspective; rather, dynamic structural transitions may be required for the selectivity and kinetics. The goal of this work is to rationally design a peptide that captures this behavior by coupling folding to surface activity, resulting in dynamic amphiphilicity of peptide-based helices. The model peptide can serve as a platform for future designs that will incorporate selectivity inherent in helical biological molecules, where binding sequences taken from nature will define the switching behavior. We couple circular dichroism and pendant bubble techniques to verify this behavior. We use circular dichroism to characterize the bulk phase ensemble average folded state as a function of salt concentration. We use the pendant bubble method to characterize the dynamics of the process, namely, surface activity with folding. These tools provide a proof of concept for a peptide design that couples folding to amphiphilicity.