4CSP:
reference: Impact of residues remote from the catalytic centre on enzyme catalysis of copper nitrite reductase., Leferink NG, Antonyuk SV, Houwman JA, Scrutton NS, Eady RR, Hasnain SS, Nat Commun. 2014 Jul 15;5:4395. doi: 10.1038/ncomms5395. PMID: 25022223

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