1DSG:
reference: Replacement of the axial histidine ligand with imidazole in cytochrome c peroxidase. 1. Effects on structure., Hirst J, Wilcox SK, Williams PA, Blankenship J, McRee DE, Goodin DB, Biochemistry 2001 Feb 6;40(5):1265-73. PMID: 11170452

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