allostery vs cooperativity in enzyme activity (EK Bio)

[astronaut135]

An enzyme may possess more than one ligand-binding site. The binding of a ligand at one site may facilitate binding of another ligand at another site on the same enzyme. This is an example of:

a) heterotrophic allostery
b) positive cooperativity
c) reversible binding
d) negative cooperativity

I thought that the answer would be a, since the ligands bind to two different sites. However the answer is b.

I guess my question is: what's the exact difference between allostery and cooperativity?

---

Members don't see this ad.

 

[Temperature101]

An enzyme may possess more than one ligand-binding site. The binding of a ligand at one site may facilitate binding of another ligand at another site on the same enzyme. This is an example of:

a) heterotrophic allostery
b) positive cooperativity
c) reversible binding
d) negative cooperativity

I thought that the answer would be a, since the ligands bind to two different sites. However the answer is b.

I guess my question is: what's the exact difference between allostery and cooperativity?

I would have chosen B since I have never seen that 'heterotropic' allostery term.... If answer A was just 'allostery', I would have picked that answer over B...

 

[FeinMS]

Let's say "A" binds to a ligand binding site to facilitate "B" binding to another site.
Heterotrophic allosteric regulator simply means different molecule (hetero) binds at somewhere else (allosteric) than the ligand. A is indeed a heterotrophic allosteric molecule of B, but there's a better answer and also we don't know if the problem is talking about the same molecule or different molecule. If the problem is talking about A binding in order to facilitate another A binding, then A is a homotrophic allosteric regulator.
Positive cooperativity means if one molecule binds, the next molecule is easier to bind. Example is O2 binding in hemoglobin.

 

[DrDreams]

An enzyme may possess more than one ligand-binding site. The binding of a ligand at one site may facilitate binding of another ligand at another site on the same enzyme. This is an example of:

a) heterotrophic allostery
b) positive cooperativity
c) reversible binding
d) negative cooperativity

I thought that the answer would be a, since the ligands bind to two different sites. However the answer is b.

I guess my question is: what's the exact difference between allostery and cooperativity?

It is positive cooperativity because of a hemoglobin example. Although it is allosteric modulation, the binding of one oxygen manipulates the structure of the 3 remaining heme groups, allowing oxygen to bind more easily than the first. This is positive cooperativity. Cooperativity is made possible by allosteric modulation which is allostery.