3GYR:
reference: Structure of phenoxazinone synthase from Streptomyces antibioticus reveals a new type 2 copper center., Smith AW, Camara-Artigas A, Wang M, Allen JP, Francisco WA, Biochemistry. 2006 Apr 11;45(14):4378-87. PMID: 16584173

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