1CPG:
reference: A cation binding motif stabilizes the compound I radical of cytochrome c peroxidase., Miller MA, Han GW, Kraut J, Proc Natl Acad Sci U S A 1994 Nov 8;91(23):11118-22. PMID: 7972020

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).