Core component 4 - Enzyme Inhibition

Question 1

How do competitive inhibitors decrease the rate of reaction?

Answer 1

They have a molecular shape complementary to the active site and similar to the substrate, so they compete with the active site meaning that there is less chance for the substrate to bind and therefore less enzyme substrate complexes are formed

Question 2

What effect does increasing the substrate concentration have on the competitive inhibitor?

Answer 2

It reduces the effect of the inhibitor because there is more chance of substrate binding to the active site

Question 3

Why do you end up with the same amount of product from the same amount of substrate with different concentrations of inhibitor?

Answer 3

Because the inhibitor can bind to the active site and unbind, in other words, inhibition is reversible. So eventually all the substrate is used up.

Question 4

How do non-competitive inhibitors decrease the rate of reaction?

Answer 4

They do not compete with the substrate but the bind to the enzyme at an ‘allosteric site’, this effects the bonds within the enzyme and therefore it’s 3-D shape including its active site so it cannot form any enzyme substrate complexes

Question 5

Relationship with final mass of product and non-competitive inhibitor concentration

Answer 5

As inhibitor concentration increases final mass of product decreases because more enzyme molecules are denatured and they cannot catalyse any more reactions so no enzyme substrate complexes can be formed

Question 6

Effect of increasing substrate concentration on non-competitive inhibition?

Answer 6

It has no effect because it is an irreversible reaction