(773b) Elucidating Protein (Folding) Kinetics Near Organic Surfaces As a Function of Surface Hydrophobicity

Protein-surface interactions are ubiquitous in biology and in modern biosensing devices, but how such interactions impact protein stability and dynamics is not well understood. Surface hydrophobicity characterized by water contact angle is often used to describe surface-induced modulations in the protein stability. The role of surface hydrophobicity in protein diffusion and folding kinetics is much less well-understood. Here, we use peptide loop-closure (end to end contact formation) as a proxy for measuring protein folding kinetics and how it is impacted by protein-surface interactions. We use self-assembled monolayers (SAMs) for which hydrophobicity can be controlled by changing the headgroup as these surfaces are routinely employed in laboratory experiments. We find that the rate of contact formation between peptide ends is significantly altered by its interactions with the SAM surface. Furthermore, the change with respect to bulk is a function of surface hydrophobicity. Interestingly, we do not find a significant impact of protein-surface interactions on protein diffusion for these small peptides diffusing around on defect-free SAM surfaces.