What is an Allosteric Enzyme?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 05 February 2017
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An allosteric enzyme is an chemical involved in the regulation of cell processes. These enzymes play a role in cell metabolism by catalyzing various events, like other enzymes, and they can also be used to control the rate of metabolism. They are used by the cell to keep operating efficiency high and to prevent the waste of energy and the unnecessary production inside the cell. Researchers who study them often work with bacteria such as Escherichia coli to learn more about how these enzymes function and what happens when their structure changes.

Function of enzymes can be changed by binding of inhibitors or activators to the active site on the enzyme. With allosteric enzymes, 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 that 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, it 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.

In addition to being used by the body, allosteric enzymes can also be harnessed by a doctor. Targeting the binding site on one could allow for unique drug delivery to change the shape, and therefore the function, of an enzyme. Allosteric modulation could be used to treat a number of medical conditions with precisely targeted therapy that may cause fewer side effects and other problems because it focuses on a specific enzyme within the body, rather than targeting a broad region.


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Post 6

@burcidi-- Enzymes are used in cancer research and I think allosteric enzymes are used a lot for anti-cancer drugs. I don't think that enzymes can stop cancer cells from dividing for now. We still have a lot to learn about enzymes, their activity is not always understood well or predicted. But allosteric enzymes can be used to change the metabolism of cancer cells and I think this is the only way in which they can be used in cancer treatment for now.

Penicilin is another drug where allosteric enzymes are used. Enzymes have already improved drugs and treatments despite ongoing research and lots of unknowns. I think things will only get better in the future. I really do believe that we will beat many illnesses one day and enzymes are going to be one of the things which helps us in doing this.

Post 5

Are studies of allosteric enzymes important for cancer research as well?

I read that what we call cancer is actually cells which keep dividing without end. And all enzymes, including allosteric ones help regulate how these cells function. From this information, can we reach the conclusion that allosteric enzymes could be used to control or prevent cancer?

For example, can we turn off the enzymes in a cell that causes the cell to divide?

I think if we could do that, we could treat and prevent cancer and many other illnesses that are caused by cells which are not functioning properly. Do you think this is possible and how close are we technologically to doing this?

Post 4

If you choose to study Biochemistry in college, you will learn a lot about allosteric enzymes and how they interact with each other and other subunits in the body. I personally really enjoyed learning about enzymes, it was probably one of my favorite topics to study in biology and biochemistry.

I think the most important knowledge I picked up from my course on enzymes is the R state and T state of allosteric enzymes. An allosteric enzyme in an R state is very active and is controlled by the activators like the article mentioned. T state, on the other hand, is when the enzyme is not very active and is controlled by inhibitors.

The other interesting thing about

allosteric enzymes is that each one has sub units. So an enzyme has four units, for example. When an inhibitor or activator attaches to one of these sub units, all of the other subunits will follow and do what that subunit does. If it is activated, they will also become more active, if it is inhibited, they will slow their activity. And once the allosteric enzyme goes into T state, it can be activated to go back to R state and vice versa.

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