Question

What would happen to the O₂-binding curve of hemoglobin when BPG is removed from its environment?

A.		The shape of the binding curve will not be affected.
B.		The sigmoid nature of the curve would diminish.
C.		The sigmoid nature of the curve would become more accentuated.
D.		Hemoglobin will not bind O2 any more.

Answer 1

Sol: B. The sigmoid nature of the curve would diminish.

Partial pressure of oxygen (PO2) is the most important factor that determines the percent oxygen saturation of haemoglobin, several other factors also influence tje affinity with which haemoglobin binds oxygen. In effect, these factors shift the entire oxygen-haemoglobin dissociation curve either to the left (higher affinity) or to the right (lower affinity).

BPG (2,3-bisphosphoglycerate) is highly charged anaion. In deoxygenated state, beta globin chains of haemoglobin binds one molecule of BPG. It reduces the O2 affinity of haemoglobin and shift the entire oxygen dissociation curve to the right. It exerts its effect on O2 affinity of haemoglobin by binding to deoxyhaemoglobin but not to oxyhaemoglobin. The greater the level of BPG, the more oxgen is unloaded from haemoglobin.