1JZL:
reference: Restricting the ligand-linked heme movement in Scapharca dimeric hemoglobin reveals tight coupling between distal and proximal contributions to cooperativity., Knapp JE, Gibson QH, Cushing L, Royer WE Jr, Biochemistry 2001 Dec 11;40(49):14795-805. PMID: 11732898

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