2FNS:
reference: Mechanism of substrate recognition by drug-resistant human immunodeficiency virus type 1 protease variants revealed by a novel structural intermediate., Prabu-Jeyabalan M, Nalivaika EA, Romano K, Schiffer CA, J Virol. 2006 Apr;80(7):3607-16. PMID: 16537628

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