I just took an exam and don\'t know if I got this question correct. I would love
ID: 59613 • Letter: I
Question
I just took an exam and don't know if I got this question correct. I would love some feedback on what the answers might be.
A. Draw the O2 binding curve for stripped/pure hemoglobin. I drew a normal sigmoidal curve.
B. Draw the O2 binding curve for stripped/pure hemoglobin treated with CO2. I drew a curve shifted right.
C. Draw the O2 binding curve for stripped/pure hemoglobin treated with CO2 and bicarbonate ion. I indicated that this curve would be the same as the one from part B, as most CO2 would end up as bicarbonate ions anyways.
D. In mutant hemoglobin, histidine is mutated to glycine. Imidazole is then added to bind to the porphoryn as histidine would have. Draw the binding curve for the mutant hemoglobin. I drew a very low, barely existent binding curve. My reasoning was that even though imidazole binds to porphoryn, the F-helix wouldn't pull be able to pull the glycine down as it would the histidine. This means that Fe+2 won't move into the plane of the porphoryn, so there's no conformational change to cause cooperative binding of O2.
Again, I have no idea if these answers are right but I would love some feedback.
Explanation / Answer
1)
The tight form of hemoglobin is called stripped and relaxed form is called Normal hemoglobin. Normal Hemoglobin exhibit positive cooperativity, whereas stripped hemoglobin does not. Therefore, sigmoidal curve will be obtained for hemoglobin for O2 binding, but stripped hemoglobin do not bind to more O2, hence it do not exhibit sigmoidal kinetics.