1NPG:
reference: Crystal structures of ferrous horse heart myoglobin complexed with nitric oxide and nitrosoethane., Copeland DM, West AH, Richter-Addo GB, Proteins 2003 Nov 1;53(2):182-92. PMID: 14517970

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