5SIC:
reference: Molecular recognition at the active site of subtilisin BPN': crystallographic studies using genetically engineered proteinaceous inhibitor SSI (Streptomyces subtilisin inhibitor)., Takeuchi Y, Noguchi S, Satow Y, Kojima S, Kumagai I, Miura K, Nakamura KT, Mitsui Y, Protein Eng 1991 Jun;4(5):501-8. PMID: 1891457

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