FIGURE 1.

Crystal structures of the three heme peroxidases that conserve the proximal Trp: CCP, APX, and LmP. The triple β-strand feature unique to CCP and LmP is colored in yellow. The loop between the A and B helices is colored in cyan. The Trp pocket, underneath the heme prosthetic group, for each enzyme is unique. LmP has the potassium ion that CCP lacks and an extra sulfur-containing residue, Cys¹⁹⁷ (C197). The large cyan spheres represent K⁺ or Ca²⁺. Figs. 1–3 were prepared with PyMOL (available on the World Wide Web).