3DCR:
reference: Crystal structure of chemically synthesized HIV-1 protease and a ketomethylene isostere inhibitor based on the p2/NC cleavage site., Torbeev VY, Mandal K, Terechko VA, Kent SB, Bioorg Med Chem Lett. 2008 Aug 15;18(16):4554-7. Epub 2008 Jul 15. PMID: 18657969

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