Enzyme kinetics 2 & Inhibition

Question 1

What are the three types of reversible inhibition and what do they bind to?

Answer 1

Competitive: I binds to free E only
Uncompetitive: I binds to ES only
Non-competitive (simple & mixed): I binds to both E and ES

Question 2

what is the competitive inhibition about?

Answer 2

1. I binds to the free E but NOT the ES complex - reduces [ES]and, hence, vo

2.Binding of I and S to enzyme is mutually exclusive (i.e. I and S CANNOT bind to E at the same time)

3.Increase of inhibitor- EI increases and contraction of es will decrease . The substrate concentration high will stop the reaction if e+e1 reversible reaction

4. If the km is increased it will increase the substrate making it bind to the enzyme letting the reaction take place.

an example is malonate completion of the succinate dehydrogenase

Question 3

What is the non-competitive inhibition about?

Answer 3

1.I can bind to both the E and ES.
Bind if the substrate is present or absent

2.The inhibitor binds to the allosteric site so the substrate can still bind to the active site forming the ESI complex which does not give product

3.The inhibitor can be released making the reaction go back so the normal reaction will make protein and the ESI complex will not

3. The vmax will go down
   Some the ES gets converted to the ESI so vmax decrease
4. Km will be normal

Question 4

what is un competitive

Answer 4

1.The opposite of competitive inhibition – I binds to ES but NOT E

2. No product is formed in the ESI
3. The inhibitor can be released so the normal reaction can take place but there is an decrease in the enzyme substrate and a decrease in the km which will lead to a decrease in the substrate
4. Adding the inhibitor makes it from the enzyme substrate complex because the reaction is getting pulled.

Question 5

What inhibitor is best for cholesterol?

Answer 5

Rosuvatin is a hydroxymethylglutaryl-CoA reductase with KI of 1.83nM which is best to treat cholesterol

Question 6

What does the irreversible inhibition do?

Answer 6

1.Irreversible inhibitors bind very tightly to an enzyme’s active site.

2.The enzymes covalent bonds binds to the above site of the enzyme causing it dead as it is stuck. e.g sarin which can kill with 1-2 minutes

Question 7

What is the uncompetitive inhibition line weaver-burk plot like?

Answer 7

Rise to a series of parrallel lines

Question 8

What is the noncompetitive inhibition line weaver-burk plot like?

Answer 8

Rise to a series of lines that intercept a -1/Km