Figure 7 - full size

 

Figure 7.
FIG. 7. The C-terminal histidine of the chains in the deoxy form. The position of this residue is almost identical in the structures at pH 5 and 7.5. Ser-93 hydrogen bonds to Asp-94 through its side chain hydroxyl group (shown as a red dotted line), but the imidazole group of His-146 is too far (>3.5 Å) from the Asp for a strong bonding interaction.

The above figure is reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 28632-28640) copyright 2004.