3HQ9:
reference: CcpA from Geobacter sulfurreducens Is a Basic Di-Heme Cytochrome c Peroxidase., Hoffmann M, Seidel J, Einsle O, J Mol Biol. 2009 Sep 6. PMID: 19735665

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