Enzyme Activity - Kinetics And Inhibition

Question 1

Define Km

Answer 1

The substrate concentration that produces a rate of reaction which is half of the maximum

Question 2

What is the significant of the Km value?

Answer 2

• Measure of the affinity of a enzyme for its substrate

- A lower Km means a HIGHER AFFINITY

Question 3

What is the y intercept of a Leinwever-Burke plot represented by?

Answer 3

1/Vmax

Question 4

How could you calculate the Km value from a Leinwever-Burke plot?

Answer 4

1/X intercept

Question 5

What is the Michaelis-Mental equation?

Answer 5

Vo = (Vmax[S] / (Km + [S])

Question 6

What is the difference between a reversible and irreversible inhibitor?

Answer 6

Reversible inhibitors bind NON COVALENTLY and can freely dissociate whereas irreversible inhibitors bind COVALENTLY

Question 7

How does competitive inhibition affect Km and Vmax?

Answer 7

• Affects Km but not Vmax
• Addition of more substrate would outcompete the competitive inhibitor for the active site, therefore Vmax can still be reached

Question 8

How does a non-competitive inhibitor affect Km and Vmax?

Answer 8

• Affects Vmax but not Km
• Affinity of enzyme for substrate does not change, however the substrate cannot bind as the binding of the inhibitor changes the shape of the active site
• Cannot reach Vmax as all enzymes cannot become fully saturated

Question 9

Define Vmax

Answer 9

The maximum rate of reaction when all enzyme active sites are saturated with substrate

Question 10

What is an enzyme?

Answer 10

Biological protein catalysis that increased the rate of a reaction by lowering its activation energy

Question 11

What shape is the graph of [S] against V?

Answer 11

HYPERBOLIC

Question 12

What is an enzyme?

Answer 12

Biological protein catalysis that increased the rate of a reaction by lowering its activation energy

Question 13

What shape is the graph of [S] against V?

Answer 13

HYPERBOLIC