Enzyme Action-The Induced Fit Model (Leaving Cert Biology): Revision Notes

Enzyme Action-The Induced Fit Model

Enzyme Action

• Substrate: the substance an enzyme combines with.
• Active site: the part of the enzyme that binds with the substrate.
• Product: the molecule produced by the action of the enzyme.
• Enzymes are specific. They react with one particular substrate. This is know as enzyme specificity.

The Induced Fit Model / The Active Site Theory

The 'induced fit model' or 'active site theory' describes the mechanics of enzyme action.

• The substrate combines with the active site of the enzyme.
• The active site changes shape slightly to make an exact fit for the substrate (induced fit).
• The enzyme and substrate form an enzyme-substrate complex.
• The enzyme changes the substrate into a product.
• The product leaves the active site.
• The enzyme is unchanged and returns to its original shape. It is ready to begin the process again.