Allosteric enzyme

Allosteric enzyme | An enzyme that exists in two structurally distinct forms, one of which is active and the other inactive. The active form of the enzyme has a quaternary structure that allows for it to interact with its substrate at the active site. However, binding of a non-substrate molecule at the allosteric site changes the conformational shape of the enzymes active site and the enzyme is inactive, and the formation of the enzyme-substrate complex in not possible.

Allosteric enzymes often catalyse initial steps in a biochemical pathways leading to the synthesis of molecules, the end product of which can act as a feedback inhibitor, binding to the allosteric site of the enzyme rendering it inactive, thereby controlling the amount of product synthesised. Allosteric enzymes may activated or more commonly inhibited by the binding of molecules to the allosteric site.