Question

why does chloride ion act as a negative allosteric effector for hemoglobin?

Answer 1

Chloride ion act as a negative allosteric effector by binding with heamoglobin. It binds more tightly with deoxyhemoglobin than hemoglobin and stabilizes the quaternery deoxy structure. it does so by neutralizing electrostatic repulsion by an excess of positive charges in the middle of the hemoglobin molecule, but without binding to any specific site. As we know only deoxyhemoglobin have affinity with oxygen, once it stabilizes does not bind to more oxygen and thus, the oxygen binding capacity of hemoglobin reduces. Hence chloride ion act as negative allosteric effector for hemoglobin molecule.