2VNX:
reference: Iron oxidation state modulates active site structure in a heme peroxidase(,)., Badyal SK, Metcalfe CL, Basran J, Efimov I, Moody PC, Raven EL, Biochemistry. 2008 Apr 15;47(15):4403-9. Epub 2008 Mar 20. PMID: 18351739

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