Hemoglobin vs Myoglobin

[osimsDDS]

Is hemoglobin effected by positive cooperativity or negative cooperativity? Because I read that myoglobin a similar heme globular protein that assists with Oxygen in the muscles does not function under pos/neg cooperativity...

I know hemoglobin is effected by either pos or neg cooperativity but im trying to figure out which one!

Thanks

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[userah]

hemoglobin acts under positive cooperativity. Since it's an allosteric enzyme, addition of one oxygen molecule increases likelihood of enzyme binding to another oxygen molecule; thus cooperativity is positive (Cooperativity is only for molecules/proteins that contain a quarternary structure)

myoglobin is a single stranded protein, thus it doesn't show cooperativity. Only binds to one molecule of oxygen, although it has a higher binding tenacity for oxygen than hemoglobin

 

[Sea of ASH]

can you guys explain Cooperativity. for some reason i dont remember reading it at all. thanks

 

[osimsDDS]

You know why ur not reading it cuz your probably using kaplan which is s***. They miss soooo much info i would advise anyone to read kaplan just for background and memory refreshment then move to cliffs of schaums (i prefer schaums). Anyways let me explain:

cooperativity is when a heme group like hemoglobin binds to oxygen. Since there are like i think 250 million oxygen molecules that can bind to hemoglobin the effect of oxygen can either be positive or negative cooperativity.

Positive cooperativity is when oxygen binds to hemoglobin and the more oxygen that binds the more affinity it has for oxygen, it wants more oxygen.

Negative cooperativity is the exact opposite when oxygen binds there will be less cooperativity of the heme group to bind to oxygen and less affinity the more oxygen there is.

So basically possitive cooperativity increases the affinity of the other binding sites (nearly 250 million for hemoglobin) and negative cooperativity decreases the affinity of other binding sites.

In the case with Myoglobin another heme globular protein that is found in muscle cells it doesnt function under cooperativity binding and has a HUGE affinity for oxygen.

 

[userah]

question. when do you get negative cooperativity? i just assumed the hemoglobin always showed positive cooperativity?

 

[osimsDDS]

I got this from wiki, PGAL and the enzyme that dehydrogenizes PGAL but i dont know exactly how it work....

An example of negative cooperativity occurring is the relationship between glyceraldehyde-3-phosphate and the enzyme glyceraldehyde-3-phosphate dehydrogenase.

 

[drtoothy]

agreed. kaplan DAT sucks, but if any of your friends have their kaplan mcat books lying around, try reading it. it does fill up a few holes they have in the blue book. i'm sure schaum's is better though.

 

[Sea of ASH]

You know why ur not reading it cuz your probably using kaplan which is s***. They miss soooo much info i would advise anyone to read kaplan just for background and memory refreshment then move to cliffs of schaums (i prefer schaums). Anyways let me explain:

thanks, your right lol, i am using kaplan, i just ordered cliffs last night, do you think that would be enough?

 

[osimsDDS]

for now im using schaums and its paying off cuz im doing destroyer in between and i can answer slash understand questions much better...i think im gonna read cliffs after schaums maybe

 

[Sea of ASH]

so the answer to my question is both huh? lol
but i heard schaums is waaaay too much detail...