2QFP:
reference: Crystal structures of a purple acid phosphatase, representing different steps of this enzyme's catalytic cycle., Schenk G, Elliott TW, Leung E, Carrington LE, Mitic N, Gahan LR, Guddat LW, BMC Struct Biol. 2008 Jan 31;8:6. PMID: 18234116

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