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. Author manuscript; available in PMC: 2011 Feb 26.
Published in final edited form as: J Mol Biol. 2009 Dec 11;396(3):510. doi: 10.1016/j.jmb.2009.12.003

Fig. 5.

Fig. 5

Hydrogen bonding of His211 in rhodopsin (A) and Meta II (B). Meta II formation is associated with a change in the hydrogen bonding network centered on His211. In rhodopsin, the backbone carbonyl of His211 forms a hydrogen bond with the side chain of Glu122, while the imidazole side chain of His211 interacts with Trp126. A shift in the position of the retinal β-ionone ring upon activation disrupts the interaction between the backbone carbonyl of His211 and Glu122, and a new hydrogen bond forms with the imidazole side chain δ-nitrogen.