Figure2. Different positions of the Rieske Iron-sulfur cluster relative to heme irons. Iron-Iron distances are taken from references 1, 2, and 3. The distance between the Rieske cluster and the low potential heme of cytochrome b is plotted on the vertical axis, and that to the heme of cytochrome c1 on the horizontal axis. Blue dots represent positions approximating the cytochrome b position, red dots approximate the cytochrome c1 position, and the green dot represents the intermediate position found in one monomer of the P65 crystal. The data labels identify the following structures: I4122- entry 1QCR (bovine tetragonal ). Chicken + stigmatellin- entry 3BCC. P65- entry 1BGY, chain E . P212121- entry 1BCC (chicken); P6522R- rabbit hexagonal; P21- beef monoclinic; P6522B- bovine hexagonal; P6522I- entry 1BE3 (flash-frozen, dehydrated beef hexagonal).