Question

Does anyone know what the difference is between an allosteric enzyme and a enzyme that is not allosteric?

Answer 1

yes, I do. =)

Answer 2

okay, JK. an allosteric enzyme is an enzyme that can be inhibited by an allosteric effector. this is a molecule that binds to a binding site off the reactive site and induces a conformation change in the enzyme, thus inhibiting it.

non-allosteric enzymes can not be effected by allosteric inhibitors. but they are, as all enzymes, vulnerable to cometitive inhibitors.

Answer 3

Thanks.

Answer 4

if you liked my answer, you are free to reward it with a medal. ;-)

Answer 5

So allosteric enzymes, can be turned on and off by the attatchment of a ligand?

Answer 6

yes. but the important thing is that this ligand doesn't bind where the substrate binds, but somewhere else on the enzyme ("action at a distance"). non-allosteric enzymes can also be turned off, but by ligands blocking the reaction site (which is the same place as the substrate woul bind).

Answer 7

Is the enzyme isocitrate dehydrogenase inactivated by NADH, in citric acid cylcle?

Answer 8

Is it an example of how allosteric enzymes are the place where the products of the cylcle are regulated?

Answer 9

Allosteric enzymes are proteins that can be binded by small molecules other than the active site that changes their activity [activator/inhibitor]. This can be seen by looking at an activity vs substrate graph. It would have a sigmoidal curve. Examples of allosteric enzymes are PFK1 and ATC [Aspartate Transcarbamoylase].

Both of these enzymes can be activated or inhibited. Inhibited doesnt mean it stops working [inactive] but it takes more substrate to redeem normal activity.

[Credential: Currently taking Biochemistry 651.... Currently have an A in the class..... My final is in 3 days.]

Answer 10

Allosteric enzyme activity can be regulated.
Normal enzymes act as ON or OFF (means 100% activity OR no activity at all) while allosteric enzyme can act at different rate (10% or any other). It is governed by binding of molecule to site which is other than active site.