1.9 Enzyme inhibition

Question 1

What are enzyme inhibitors?

Answer 1

Substances that directly or indirectly interfere (幹擾) with the function of the active site of an enzyme and so reduce its activity.

Question 2

What are the 2 types of enzyme inhibitors?

Answer 2

1. competitive inhibitors
2. non-competitive inhibitors

Question 3

What are competitive inhibitors?

Answer 3

Inhibitors that bind to the active site of the enzyme.

Question 4

What are non-competitive inhibitors?

Answer 4

Inhibitors that bind to a binding site which is not the active site of the enzyme.

Question 5

How do competitive inhibitors decrease the rate of reaction?

Answer 5

They have a similar shape to the substrate, so they can bind to the active site. This prevents the substrates from binding to the active site, and so decreases the rate of reaction.

Question 6

Are competitive inhibitors permanent or temporary? What does it mean?

Answer 6

Permament. This means that when competitive inhibitors leave the active site, other substrates can bind to the active site.

Question 7

What will happen to the effect of competitive inhibitors as the substrate concentration increases? Why?

Answer 7

The effect of competitive inhibitors is reduced, because the higher the substrate concentration, the more likely it is that substrates will bind to active sites rather than inhibitor molecules.

Question 8

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

Answer 8

They attach themselves to a binding site which is not the active site. This changes the shape of active site, so substrates can no longer bind to the active site and the active site can’t function.

Question 9

What will happen to the effect of non-competitive inhibitors as the substrate concentration increases? Why?

Answer 9

The effect of non-competitive inhibitors doesn’t decrease, because non-competitive inhibitors do not compete with the substrate to bind to the active site.