1NM4:
reference: A redox switch in CopC: an intriguing copper trafficking protein that binds copper(I) and copper(II) at different sites., Arnesano F, Banci L, Bertini I, Mangani S, Thompsett AR, Proc Natl Acad Sci U S A 2003 Apr 1;100(7):3814-9. Epub 2003 Mar 21. PMID: 12651950

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