1.13.11.92 | structure to 1.5 A resolution. The structure is monomeric, predominantly helical-helical, and comprised of two domains. Helices H2, H6, H8, and H17 form the heme binding cleft and walls of the active site channel. Residues His318, Thr323, and Arg566 are located near the catalytic tyrosine, Tyr386, at the apex of the channel, where they interact with a chloride ion. Two extended inserts are present on the surface of the enzyme that restrict access to the distal face of the heme |