We describe the rational design of amphiphilic helical peptides with controllable charge separation and tunable surface activity, where the dynamics of surface activity are an outcome of helical folding. The fundamentals of peptide folding and adsorption are investigated using a liquid crystal system. The thermotropic liquid crystals serve as a model fluid (i.e. oil) for the optical examination of dynamic molecular events at the aqueous/oil interface. This setup allows for the label-free detection of adsorbates with high sensitivity without limiting the mobility of the interface. Previously, similar liquid crystal experiments have been used to examine surfactants, lipids, and DNA. Our studies examine the time-dependent behavior of our periodically sequenced peptides and compare them with two well-cited protein systems, bovine serum albumin (BSA) and Lysozyme. We show that the dynamics can be quantified by the cooperative tilting of the liquid crystal (see figure), where proteins and peptides display unique organizational behavior at the interface. Subsequently, the adsorption behavior can be coupled to the bulk folded state of the peptide using circular dichroism to show that the folded population can be controlled with changes in electrolyte concentration. Taken together, we present a method to investigate surface patterning and peptide partitioning using liquid crystals, where competitive adsorption of peptides and proteins can be used to define the thermodynamics and kinetics of adsorption.

Dynamics of periodically sequenced polypeptides at the aqueous/liquid crystal interface

251st National Meeting (2016)

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