2WWT:
reference: Crystal structure of an intracellular subtilisin reveals novel structural features unique to this subtilisin family., Vevodova J, Gamble M, Kunze G, Ariza A, Dodson E, Jones DD, Wilson KS, Structure. 2010 Jun 9;18(6):744-55. PMID: 20541512

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