Question

question 22
which of the following statements best describes the induced fit model of enzyme activity?
the binding of substrate depends on the conformation of the active site.
the binding of an activator alters the conformation of the active site to bind products more tightly.
the binding of substrate changes the conformation of the active site to bind substrate more tightly.
the binding of a competitive inhibitor changes the shape of the active site so that it binds substrate less tightly.

Explanation:

The induced - fit model of enzyme activity states that when the substrate approaches the enzyme, the binding of the substrate causes a conformational change in the active site of the enzyme. This change in conformation allows the enzyme to bind the substrate more tightly.

• The first option ("The binding of substrate depends on the conformation of the active site") is more in line with the lock - and - key model (where the active site has a pre - existing, rigid conformation that fits the substrate).
• The second option ("The binding of an activator alters the conformation of the active site to bind products more tightly") is about the effect of an activator on product binding, not the induced - fit mechanism for substrate binding.
• The fourth option ("The binding of a competitive inhibitor changes the shape of the active site so that it binds substrate less tightly") is about competitive inhibition, not the induced - fit model.

Answer:

The binding of substrate changes the conformation of the active site to bind substrate more tightly.