3VAU:
reference: Unveiling the three-dimensional structure of the green pigment of nitrite-cured meat., Yi J, Richter-Addo GB, Chem Commun (Camb). 2012 May 4;48(35):4172-4. Epub 2012 Mar 20. PMID: 22430128

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