2C7L:
reference: Local protein flexibility as a prerequisite for reversible chromophore isomerization in alpha-phycoerythrocyanin., Schmidt M, Krasselt A, Reuter W, Biochim Biophys Acta. 2006 Jan;1764(1):55-62. Epub 2005 Nov 21. PMID: 16377266

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