1CBM:
reference: The 1.8 A structure of carbonmonoxy-beta 4 hemoglobin. Analysis of a homotetramer with the R quaternary structure of liganded alpha 2 beta 2 hemoglobin., Borgstahl GE, Rogers PH, Arnone A, J Mol Biol 1994 Feb 25;236(3):817-30. PMID: 8114096

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