Lecture 12

Question 1

What are the two types of enzyme inhibitors?

Answer 1

Reversible and irreversible

Question 2

Reversible inhibition?

Answer 2

Can be competitive or non-competitive (pure or mixed)

Question 3

How are competitive and non-competitive inhibotirs different?

Answer 3

Competitive Inhibitors bind to the enzymes active site

Non-competitive Generally binds at a seperate site

Question 4

Competitive Inhibition?

Answer 4

• competes with substrate for active site of enzyme
• Reaction doesn’t occur when inhibitor is bound
• prevents binding of substrate, instead forms EI complex
• inhibition can be overcome by adding more substrate
• Km increases, Vmax remains same

Question 5

Non Competitive Inhibition?

Answer 5

• Inhibitor binds at a site on the enzyme other than active sit
• Enzyme does not work when inhibitor is bound
• lowers E concentration and Vmax
  -depending on where it bound, may or may not eaffect binding of s
  ubstrate

Question 6

How do pure and mixed inhibitors affect binding of substrate?

Answer 6

Pure does not affect binding of substrate - no effect to Km. Mixed does because it- Km increases. distorts the active site

Question 7

Are competitive and non-competitive inhibitors reversable?

Answer 7

Yes, because the inhibitors to do bind covalently to the enzyme.

Question 8

What are irreversible enzyme inhibitors?

Answer 8

These bind covalently to enzymes and inactivate them irreversibly as they remain permanently bound to the enzyme

Question 9

What is a transition state?

Answer 9

The transition state is a chemical species that is intermediate in structure between the substrate and the product.

• tightest binding occurs between TS and E
• TS analoges make ideal enzyme inhibitor