Figure 2 - full size

 

Figure 2.
Fig. 2. Redox-coupled conformational changes in Asp-51. (A) Stereoscopic drawing of the hydrogen-bond network in the fully oxidized and reduced (blue structure) states at 1.8- and 1.9-Å resolution, respectively, viewed from the intermembrane side. The two histidines bound to Fe[a] (heme a iron), are not shown. (B) The hydrogen-bonding structure of Asp-51 in the oxidized (Left) and reduced (Right) states. The smooth thick curve denotes the molecular surface to which the water molecules in the intermembrane space are accessible. The conformational changes induced by reduction of the enzyme are shown by blue structures in Right. The blue (A) and black (B) balls represent the fixed water molecules. The dotted lines denote hydrogen bonds. The double-headed dotted arrows show a possible movement of the water molecule from Arg-38 to Tyr-371.