3PYK:
reference: Human Carbonic Anhydrase II as a host for piano-stool complexes bearing a sulfonamide anchor., Monnard FW, Heinisch T, Nogueira ES, Schirmer T, Ward TR, Chem Commun (Camb). 2011 Aug 7;47(29):8238-40. Epub 2011 Jun 27. PMID: 21706094

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