. Author manuscript; available in PMC: 2014 Mar 7.

Published in final edited form as: J Phys Chem B. 2013 Feb 25;117(9):2653–2661. doi: 10.1021/jp3117227

Table 2.

Breakdown of the proton tautomer distribution for histidine residues in the various peptides at pH=7. HIP indicates a doubly protonated immidazole ring, while HID and HIE indicate singly prototonated immidazole with the excess proton residing on the δ nitrogen and ε nitrogen, respectively.

System		pH=7
System		HIP	HID	HIE
MII	His9	0.28	0.56	0.15
MII	His12	0.51	0.43	0.06

MII-E11A	His9	0.22	0.57	0.21
MII-E11A	His12	0.10	0.48	0.42

MII-N5R:E11A:H12K	His9	0.19	0.65	0.16