1RPS:
reference: Crystallographic analysis of the interaction of nitric oxide with quaternary-T human hemoglobin(,)., Chan NL, Kavanaugh JS, Rogers PH, Arnone A, Biochemistry 2004 Jan 13;43(1):118-32. PMID: 14705937

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