Question

One of the treatments for breast cancer is the administration of selective aromatase inhibitors. Aromatase is an enzyme involved in the synthesis of various estrogens, such as estrone and estradiol. Aromatase inhibitors can be divided into two categories, type I and type II. Type I inhibitors are irreversible inhibitors of aromatase. Type II inhibitors are competitive inhibitors of aromatase. Given what you know about enzyme inhibition, explain the differences between irreversible and competitive enzyme inhibition.

Answer 1

Enzyme inhibitors also occur naturally and are involved in the regulation of metabolism. as enzymes in a metabolic pathway can be inhibited by downstream products.The binding of an inhibitor can stop a substrate from entering the enzyme's active site and hinder the enzyme from catalyzing its reaction. Inhibitor binding is either reversible or irreversible. Irreversible inhibitors usually react with the enzyme and change it chemically.

Competitive enzyme inhibition.

The substrate and inhibitor cannot bind to the enzyme at the same time, as shown in the figure on the right. This usually results from the inhibitor having an affinity for the active siteof an enzyme where the substrate also binds the substrate and inhibitor compete for access to the enzyme's active site

Irreversible  inhibition

Irreversible inhibitors display time-dependent inhibition.Irreversible inhibitors usually covalently modify an enzyme, and inhibition can therefore not be reversed. Irreversible inhibitors often contain reactive functional groups such as nitrogen mustards, aldehydes, haloalkanes, etc.