Fig. 4.

Structure of BthA. a Ser257 is positioned between the 6c heme, coordinated by His 371 and Tyr463, and the 5c peroxidatic heme, coordinated by His 192. b Lys444 mediates a water network between the propionate groups of the 5c and 6c hemes. c An intramolecular disulfide between Cys415 and Cys430 is located near the 6c heme and is surrounded by tyrosine and tryptophan residues. Peptide and heme carbon shown in green and purple, respectively. Oxygen, nitrogen, sulfur, and iron shown in red, blue, yellow, and orange, respectively. Peptide backbone shown in cartoon representation and sidechains and hemes shown in stick representation. Side-chain α-carbon and water shown as spheres