CO and hemoglobin curve

[anbuitachi]

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Hi in EK Bio, it says CO, which has 200x affinity for hemoglobin than does oxygen shifts oxygen dissociation curve from hemoglobin to the LEFT.

Why is this? I know other stuff like CO2, H+ shift it to the right... why does CO move it to the left?

Thanks

 

[PiBond]

Hi in EK Bio, it says CO, which has 200x affinity for hemoglobin than does oxygen shifts oxygen dissociation curve from hemoglobin to the LEFT.

Why is this? I know other stuff like CO2, H+ shift it to the right... why does CO move it to the left?

Thanks

there's an increased affinity of hemoglobin for oxygen (due to CO binding) and therefore less oxygen gets delivered to the tissues. hence the leftward shift.

CO makes hemoglobin "love" oxygen even more and thus the bound oxygen doesn't want to leave. then you end up getting hypoxic tissues and other bad stuff

 

[Charles_Carmichael]

Remember that the Hb binding curve is sigmoidal in shape, which is referring to its cooperativity (positive cooperativity). So, when one O2 binds to a site of Hb, it makes the next O2 binding easier, which makes the next one easier, etc. Similarly, when an O2 dissociates from an Hb binding site, it makes the dissociation of the next one easier, etc.

Now, the problem is that when CO binds a site on Hb, it binds with very high affinity and doesn't dissociate easily. So, it makes it harder for the other O2 molecules to dissociate. So, you can see how having CO take up one or two sites on Hb can make it harder for O2 molecules in the other sites to dissociate due to this cooperativity. Hope this helps.

 

[anbuitachi]

oh wow, never thought of that, thanks!