2BS2:
reference: Evidence for transmembrane proton transfer in a dihaem-containing membrane protein complex., Madej MG, Nasiri HR, Hilgendorff NS, Schwalbe H, Lancaster CR, EMBO J. 2006 Oct 18;25(20):4963-70. Epub 2006 Oct 5. PMID: 17024183

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