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. Author manuscript; available in PMC: 2008 Jun 23.
Published in final edited form as: J Am Chem Soc. 2003 Nov 12;125(45):13804–13818. doi: 10.1021/ja035654x

Figure 2.

Figure 2

Possible conformers and tautomers of His64 that have been assigned to conformational substates. (a) A0.29,32 The distal His64 is swung out of the pocket away from the ligand. The carbons of the imidazole side chain are labeled Cα–Cγ. (b) A1.19,20,29 The Nε–H is in the pocket and oriented toward the ligand. (c) A1.28,34 The Nδ–H is oriented toward the solvent, and the lone pairs of the Nε interact with the ligand. (d) A3.29,45,80 The Nε–H is in the pocket and is very close to and interacts strongly with the ligand. There may be a hydrogen bond between Nε–H and the CO. (e) A121,34 or A3.19 The Nδ–H is in the pocket near the ligand. (f) A1.45 Both Nε–H and Nδ are in the pocket. There is moderate interaction between His64 and the ligand.