Resolv Grad Fellow Saurabh Belsare explores Solvation Entropy in Enzyme Active Sites

Using a spatially resolved analysis of hydration patterns, intermolecular vibrations, and local solvent entropies, the T. Head-Gordon group in collaboration with RESolv researcher Matthias Hayden and Viren PattiĀ  have identified distinct classes of hydration water and follow their changes upon substrate binding and transition state formation for the designed KE07 and KE70 enzymes and their evolved variants. We observe that differences in hydration of the enzymatic systems are concentrated in the active site and undergo significant changes during substrate recruitment. For KE07, directed evolution reduces variations in the hydration of the polar catalytic center upon substrate binding, preserving strong protein-water interactions, while the evolved enzyme variant of KE70 features a more hydrophobic reaction center for which the expulsion of low-entropy water molecules upon substrate binding is substantially enhanced. While our analysis indicates a system-dependent role of solvation for the substrate binding process, we identify more subtle changes in solvation for the transition state formation, which are less affected by directed evolution.