Figure 6.
The heme-binding pocket. (A) The amino acids from two adjacent subunits forming the heme-binding pocket are indicated. (B) The heme, the two His18 iron-binding residues, and the residues Arg22 and Phe14 from each chain are shown as sticks, along with their associated electron density maps (2Fo − Fc) contoured at 1.5 σ. (C) The surface of one heme-binding pocket and the heme are shown. The backbone of one monomer is colored with turquoise and that of the adjacent monomer with bronze. The interactions between Arg22 and the heme propionate are indicated with black dotted lines.