Effects of Protein Conformation on Charge Regulation

Proteins change charge in response to their electrostatic environments, by changing protonation patterns of titratable residues. This charge regulation is important for modeling protein interactions, including proteins that undergo conformational change, such as intrinsically disordered proteins, and enzymes that are allosterically controlled. We construct grand canonical partition function models that take account of flexibility by incorporating it into the relevant partition functions for each proton occupancy pattern. We use this model to analyze titration data for selected small molecule sequences, including dicarboxylic acids, diamines, and peptides.