Enzyme inhibitors

Question 1

What is the purpose of inhibitors?

Answer 1

To regulate enzyme activity so that products dont accumulate

Question 2

What are examples of reversible inhibitors?

Answer 2

Competitive and non-competitive - they can switch on and off

Question 3

What happens in competitive inhibition?

Answer 3

1. Competitive inhibitor has similar shape to substrate + can bind to active site
2. Prevents substrate frim binding + forming product
3. Enzyme is now inhibited

Question 4

How long to competitive inhibitors bind for?

Answer 4

Bind temporarily to active site - effect is reversible

Question 5

Can you reach the Vmax with competitive inhibitors?

Answer 5

Yes

Question 6

What effect do competitive inhibitors have on the rate of reaction?

Answer 6

Depends on the concentration if substrate to inhibitor

Greater the inhibitor conc, greater rate of inhibition
Greater the substrate conc, greater rate of reaction

Question 7

What are examples of competitive inhibitors?

Answer 7

Statins and aspirin

Question 8

What happens in non competitive inhibition?

Answer 8

1. Non competitive inhibitor binds to allosteric site
2. Causes tertiary structure of enzymes active site to change, so shape changes often permanently
3. Active site not complimentary to substrate + product cant be formed
4. Enzyme inhibited

Question 9

What effect does non competitive inhibition have on rate of reaction?

Answer 9

Increasing substrate conc has no effect, + increasing inhibitor conc will decrease rate because less active sites are available

Question 10

Can non competitive inhibitors reach the vmax?

Answer 10

No - shape changes + binds permanently so substrate cant bind

Question 11

What are examples of non competitive inhibitors?

Answer 11

Organophosphates and proton pump inhibitors (PPIs)

Question 12

What is end-product inhibition an example of?

Answer 12

Negative feedback

Question 13

What can end-product inhibition help to reduce?

Answer 13

Product buildup

Question 14

What happens in end-product inhibition?

Answer 14

1. Substrate forms enzyme-substrate complex + product formed
2. Product may act as non-competitive inhibitor, binding to allosteric site on og enzyme
3. Causes enzymes active site to no longer be complimentary to substrate + reaction inhibited

Question 15

What is an example of end-product inhibition?

Answer 15

Glycolysis (stage of respiration) + the enzyme phosphofructokinase (PFK)