2CUA:
reference: The CuA domain of Thermus thermophilus ba3-type cytochrome c oxidase at 1.6 A resolution., Williams PA, Blackburn NJ, Sanders D, Bellamy H, Stura EA, Fee JA, McRee DE, Nat Struct Biol 1999 Jun;6(6):509-16. PMID: 10360350

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