Actions of Drugs on Enzymes

Question 1

What are enzymes?

Answer 1

• Enzymes are proteins that catalyse the formation of a product from a substrate. Drug inhibition of the enzyme impairs formation of the product.

Question 2

Enzyme inhibition can be?

Answer 2

• Competitive - the drug binds to the same site on the enzyme as the substrate.
• Non-competitive - the drug-bound enzyme can still bind the substrate.

In addition, enzyme inhibition can be:

• Reversible
• Irreversible - causing permanent loss of function (until more enzyme is synthesised).