The sigmoid (S-shaped) binding curve that describes the interaction of O₂ with hemoglobin is a direct consequence of A) allosteric regulation by 2,3-bisphosphoglycerate. B) cooperativity among subunits. C) covalent bonds between alpha beta?heterodimers. D) orientation of histidine residues near the heme groups. E) reversible oxidation and reduction of heme iron atoms.

Question

Quizplus · Accepted Answer

The sigmoid binding curve is characteristic of cooperative binding, which occurs when the binding of one ligand molecule affects the binding affinity of subsequent ligand molecules. In the case of hemoglobin, binding of the first oxygen molecule increases the affinity of the remaining subunits for oxygen, resulting in the sigmoid binding curve. This is a consequence of cooperativity among the subunits. The other choices do not explain the sigmoid binding curve observed for O₂ and hemoglobin.

The Sigmoid (S-Shaped) Binding Curve That Describes the Interaction of O2

The Sigmoid (S-Shaped) Binding Curve That Describes the Interaction of O₂