Allosteric regulator

Both allosteric regulators and non-competitive inhibitors act in the same way in that they both effect enzyme activity by binding to the enzyme at a site which is NOT the active site. As a result of the binding of the allosteric regulator or non-competitive inhibitor, the enzyme undergoes a conformational change which effects the binding of the substrate to the active site. However, there are two important differences between an allosteric regulator and a non-competitive inhibitor:

1.Allosteric regulators are always reversible. They regulate important pathways in cells so they have to be reversible. Non-competitive inhibitors, on the other hand, are usually irreversible.

2.Allosteric regulators can be positive as well as negative regulators. In other words, binding of some allosteric regulators can actually serve to INCREASE the rate of a particular reaction. Non-competitive inhibitors, on the other hand, always act to DECREASE the rate of a reaction - they cannot increase enzyme activity.

Just want to add a little something to your answer bio_man. Basically with any allosteric enzyme, inhibitors or activators, also known as effectors or regulator molecules, actually bind to a different site on the enzyme. This changes the structure of the enzyme, consequently altering its function. When an inhibitor binds to an allosteric enzyme, the enzyme is effectively turned off, and no longer able to function in the body. Activators, on the other hand, turn the enzyme on so that it can perform a function. The regulator molecules can detach as needed. Using this system, cells can regulate the activity of enzymes in response to changing situations, activating enzymes as needed and deactivating them when it does not want them to work. The binding site where a regulator molecule attaches is known is known as the allosteric site on the enzyme. Allosteric regulation of enzymes involves a number of different molecules which can fit on this site, much like keys fit into a lock. With inhibition, the enzyme is maintained so that it will be ready when needed, but won't function before it is required, and with activation, the allosteric enzyme is kicked into gear so that it can perform a desired metabolic function. The body balances the numbers of active and inactive enzymes to modulate a wide variety of biological processes.

Thank you Star!