Oxygen Binding in Cyanmet Hybrid and Normal Hemoglobins: Applicability of Sequential and Two-State Concerted Models

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Science  03 May 1974:
Vol. 184, Issue 4136, pp. 577-579
DOI: 10.1126/science.184.4136.577


The cyanmet hybrid hemoglobins α2β+CN2 and α+CN2β2 are widely held to be similar or equivalent in structure and subunit interactions to the partially oxygen-liganded species α2(β • O2)2 and (α • O2)2β2, respectively. An analysis of precise data on oxygen binding to the cyanmet hybrids and normal hemoglobin shows that if this is the case, then cooperative ligand binding in hemoglobin is more properly described by some model of the sequential type than by any twostate concerted model.