Figure 6.

Wall-eyed stereoview of the complex III active site. Two zinc ions are shown as silver-gray spheres, and the bridging water/hydroxide is shown as a red sphere. All metal-coordinating residues and the homoserine product are shown as ball-and-stick representations. All oxygen atoms are colored red and all nitrogen atoms blue. The carbon atoms in the N-acyl-l-homocysteine molecule are colored yellow and the carbon atoms in the coordinating residues white. Electron density maps (with 2F_o − F_c coefficients) are colored blue at 6σ around the zinc atoms and at 1σ around the N-acyl-l-homocysteine product. The Zn1−Zn2 distance is given in angstroms and indicated with a dashed black line.