Oxygen Haemoglobin Dissociation Curve

[coreytayloris]

Why does Carbon Monoxide make the heamo globin curve shift to the left (meaning it has a higher affinity for oxygen) but Carbon Dioxide shifts it to the right (meaning it has a lower affinity for oxygen) ?
Sorry was just reading about it, and couldnt quite figure it out.
I know it says carbon monoxide has a really high affinity for heamoglobin but then how would that result in haemoglobin having a really high affinity for oxygen and the curve shifting to the left!?
Like both cases cause tissue hypoxia but the curve shifts different ways?!

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[Salpingo]

From my understanding, CO binds avidly to an actual oxygen binding site, inducing conformational change into the R-state, which means the hemoglobin as a whole has a higher affinity for oxygen. Its essentially the Bohr effect; just as an oxygen molecule would induce further oxygen binding, CO (which essentially acts as a super oxygen molecule), induces further oxygen binding.

Carbon dioxide does not directly bind to the oxygen binding site. It acts indirectly in the RBC by producing a more acidic environment, and directly by binding to a non-oxygen binding site. Both induce conformational into the T-state.

Hope that's right/helps.

 

[coreytayloris]

Ah yes, brilliant thanks buddy!