Competitive Inhibition

In this kind of inhibition there is a competition between the inhibitor and the substrate for the same binding site. Thus if one raises the concentration of the substrate high enough the effect of the inhibitor will be overcome. That is, the can still be reached in spite of the presence of the inhibitor, i.e. it is unchanged. On the other hand, the is changed. It is diagnostic of competitive inhibitors that they cause an alteration of the but the is unchanged.

Competitive inhibitors are quite common in nature. They often bear obvious structural relationships to the substrate. It is common for products of a reaction to be competitive inhibitors, and this is a form of biological control as it prevents excessive build up of the product.

Invertase, or -D-glucosidase, is an enzyme which hydrolyzes sucrose into its component monosaccharides, glucose and fructose. However, glucose is a competitive inhibitor of invertase, -D-glucosidase, or -fructofuranosidase. This is one of the simplest forms of biological control. When the concentration of product builds up it turns off its own formation.

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