What is an allosteric site on an enzyme?

An allosteric site is a specific region on an enzyme where a molecule can bind and influence the enzyme's activity.

In more detail, enzymes are proteins that catalyse biochemical reactions. They have an active site where the substrate binds and the reaction takes place. However, some enzymes also have one or more allosteric sites. These are distinct from the active site and are the places where regulatory molecules can bind. The binding of a molecule to the allosteric site can change the shape of the enzyme, which in turn can either enhance or inhibit the enzyme's activity.

The molecules that bind to the allosteric site are often products of the enzyme's reaction, or other molecules involved in the cell's metabolic processes. This allows the cell to regulate the enzyme's activity in response to changes in the cell's environment or needs. For example, if the product of an enzyme's reaction starts to accumulate, it can bind to the allosteric site and inhibit the enzyme, slowing down the reaction and preventing the product from building up too much. This is known as feedback inhibition.

Allosteric regulation is a key mechanism by which cells control their metabolic processes. It allows them to respond quickly and efficiently to changes in their environment or internal state, and to maintain a stable internal environment despite external fluctuations. Understanding how allosteric regulation works is therefore crucial for understanding how cells function, and it is also an important area of research in drug development, as drugs that target allosteric sites can be used to control the activity of enzymes involved in disease processes.