1USB:
reference: Incorporation of a single His residue by rational design enables thiol-ester hydrolysis by human glutathione transferase A1-1., Hederos S, Broo KS, Jakobsson E, Kleywegt GJ, Mannervik B, Baltzer L, Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13163-7. Epub 2004 Aug 27. PMID: 15333749

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