1FIZ:
reference: Effector sites in the three-dimensional structure of mammalian sperm beta-acrosin., Tranter R, Read JA, Jones R, Brady RL, Structure Fold Des 2000 Nov 15;8(11):1179-88. PMID: 11080640

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