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. Author manuscript; available in PMC: 2016 Jan 1.
Published in final edited form as: J Am Chem Soc. 2015 Sep 30;137(40):13024–13030. doi: 10.1021/jacs.5b07761

Figure 3. pH-dependent dissociation of a model crystallite.

Figure 3

a, Initial structure, consisting of 16 10-unit chains in a 4×4 arrangement (top), and the final snapshot at pH 7 (bottom). b, Average inter-chain hydrogen bonds per glucosamine residue as a function of simulation time at several pH conditions. c, Hydration number and degree of protonation of individual amine groups mapped onto the final snapshot at pH 7. The hydration number (0–4) is indicated by a color scale from green to magenta. The degree of protonation (0–1) is indicated by a color scale from blue to red. Hydration number is defined as the number of water oxygens within 3.5 Å of the amine nitrogen, while the degree of protonation of an amine group is between 0 (always deprotonated) and 1 (always protonated). Both quantities are the averages over the last 0.5-ns of the pH 7 replica. d, Hydration number and degree of protonation of individual amine groups of an isolated chitosan chain in water at pH 7. Data taken from the CpHMD simulation of a single 5-unit chitosan.