Some Blood questions

[DrDDSman]

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Hey everyone. I'm having some issues grasping the Bohr shift and cooperativity. Can someone explain it in a simple way?

Also, when CO2 is in the carbonic acid form, is the carbonic acid in the blood plasma, or is it in the RBC? I wasn't sure about that. From my understanding, its in the erythrocyte, right?

 

[Decan]

You're right...H2CO3 is in the RBC.

Check out this site for the Bohr shift....http://www.bio.davidson.edu/Courses/anphys/1999/Dickens/Oxygendissociation.htm

If something doesnt make sense, let me know.

 

[denticus]

Cooperativity - with regards to hemoglobin, you'll notice that each hemoglobin has 4 heme groups, each of which can bind 1 oxygen molecule. By cooperativity, all it's saying is that as 1 oxygen binds 1 heme this will induce a conformation change in the hemoglobin itself resulting in an increased affinity of the other unbound heme groups to oxygen. As more heme groups bind more oxygen molecules, the affinities of the remaining unbound heme groups to oxygen will increase more and more until the hemoglobin is saturated with oxygen. This is known as positive cooperativity. Negative cooperativity takes place in other enzyme/substrate relationships where the binding of one substrae to the enzyme will act to decrease the enzymes affinity for subsequent substrates. Hope this helps.

 

[DrDDSman]

Thanks guys. It makes some sense now.

 

[biocmp]

Just to add some material not worth anything, don't forget:

That increasing order of oxygen affinity goes:

Myoglobin> Fetal Hemoglobin > hemoglobin

Myoglobin has a higher affinity for oxygen than fetal hemoglobin, because the fetus's hemoglobin is used to distribute oxygen to some of the mother's muscles.

The fetus' hemoglobin has a higher affinity, because it must be able to "take" some of the mother's oxygen from her normal hemoglobin.

and finally don't forget that Eukaryotic hemoglobin is made up of 4 subunits. 2-alpha, and 2-beta subunits.

would anyone care to tell me what level of protein structure I just referred to and why?

 

[jdoc04]

In that chart what does DPG stand for?

 

[biocmp]

DPG = diphosphoglycerate, an organic phosphate.

 

[DrDDSman]

nd finally don't forget that Eukaryotic hemoglobin is made up of 4 subunits. 2-alpha, and 2-beta subunits.

would anyone care to tell me what level of protein structure I just referred to and why?

Sounds like quaternary structure right? Because multiple subunits at as one functional protein. Also I think you mean "vertebrate hemoglobin" instead of "eukaryotic hemoglobin" If i'm not mistaken, some eukaryotes like arthropods have hemolymph instead of blood. I'm not sure what the structure of the heme groups in these animals are (maybe 4 subunits?). Any ideas? Eitherway, I don't think this fact is relevant to the DAT.