3CBJ:
reference: Displacement of the occluding loop by the parasite protein, chagasin, results in efficient inhibition of human cathepsin B., Redzynia I, Ljunggren A, Abrahamson M, Mort JS, Krupa JC, Jaskolski M, Bujacz G, J Biol Chem. 2008 Aug 15;283(33):22815-25. Epub 2008 May 30. PMID: 18515357

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