Enzyme inhibition

Question 1

Is enzyme inhibition reversible or irreversible?

Answer 1

Both

Question 2

What are the characteristics of an irreversible inhibitor? (3)

Answer 2

Rarely natural
Chemically reactive
For a COVALENT bond with specific AA chain

Question 3

What is an example of an irreversible inhibitor and what does it do?

Answer 3

Acetylcholinesterase

Breaks down acetylcholine to choline and acetic acid

Question 4

What are the characteristics of a reversal inhibitor?

Answer 4

Do not react covalently
Show rapid equilibrium binding to E
Give instantaneous inhibition

Question 5

What are the 3 classes of reversible inhibitors:

Answer 5

Competitive
Non competitive
Uncompetitive

Question 6

What is the Lineweaver Burke plot?

Answer 6

Measurement of Km and Vmax

Question 7

What is competitive inhibition? (3)

Answer 7

Most common inhibitor
Inhibitor binds to active site (higher affinity)
Inhibitor cannot act as substrate

Question 8

What is methotrexate?

Answer 8

Competitive inhibitor

Question 9

What is non-competitive inhibition?

Answer 9

Rare
Inhibitor binds to E on a different site
Allows S to bind
Prevents reaction proceeding

Question 10

What is uncompetitive inhibition?

Answer 10

Very rare
Inhibitor binds to E on allosteric site after S has bound
Slows reaction down