How carbon monoxide shifts the ODC to left side

how carbon monoxide shifts the ODC to left side

It’s all about the affinity of Hb(FOR OXYGEN). Anything which increases this affinity FOR OXYGEN will shift curve to left and vice-versa. CO binds with Hb with 240times affinity more than O2 and this cause ALLOSTERIC change in Configuration of Hb such that all those Hb molecules which have even a single molecule of CO with other 3 mols of O2: all those Hb fail to unload even these 3 molecules of O2 at level of tissues causing Hypoxia. This means that binding of even a single mol of CO will increase the affinity of Hb fOR OXYGEN such that it will not unload even those Oxygen which it has. So This extreme increased affinity causes Left shift

Carbon monoxide has more affinity towards Hb as compare to oxygen…so it will displace oxygen and itself will bind to Hb…so there will be release of oxygen from Hb which will shift the curve towards left…And in presence of CO if oxygen wants to bind with Hb,the partial pressure of oxygen have to be very high which will also shift the curve towards left