Figure 6. pH-responsive predictions from the CpHMD simulations.

a, Intermolecular hydrogen bonds per glucosamine residue at different pH. Data points are the averages over the final 3 ns of each pH condition. Error bars represent the standard deviation. Inset are final snapshots at pH 4 and 8.5, with neutral and charged residues colored blue and red, respectively. b, The fraction of unprotonated amines at different pH conditions for a single glucosamine monomer, a single 5-residue chain, and the model crystallite. The solid lines are the best fits to the Hill equation (single chain and crystallite) or Henderson-Hasselbalch equation (monomer). Unprotonated fractions were averaged over the final 5 ns of the simulations for the monomer and single chain, and over the final 3 ns of the simulation for the model crystallite. Experimental data are adapted from Ref.²⁹ c, pH-dependent free energy of dissociation of the model crystallite. The free energy of dissociation at pH 8.5 was used as a reference.