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. Author manuscript; available in PMC: 2006 Jun 27.
Published in final edited form as: J Mol Biol. 2005 Aug 19;351(3):573–597. doi: 10.1016/j.jmb.2005.05.053

Figure 3.

Figure 3

H-bonding around the high potential cyt b heme. (a)- Heme bH viewed from helix B. Water W4 bridges between the two heme propionate side chains, while W5 bridges between a propionate and the heme axial ligand His97. Arg100 interacts directly with this “bent” propionate, and via unlabeled water molecule W6 with the carbonyl O of His97. W5 is also H-bonding with backbone atoms of helix A, which has been removed from this view for clarity. (b). - The same region viewed from the heme position, looking toward helices A and B. The heme is removed except the two propionate side chains. Intercalation of waters W3 and W5 in the helical backbone of Helix A can be seen. Waters W1-3 are discussed in the text in connection with antimycin binding. The map is a 2Fo-Fc map calculated from data between 15 and 2.1 Å, sharpened with B −20, and contoured at 1.8 σ (a) or 1.7 σ (b).