Experiment 10: Enzyme Kinetics

Question 1

What is kinetics?

Answer 1

Kinetics is the brand of science concerned with the rates of chemical reactions.

Question 2

The rate constant k1 describes which reaction?

Answer 2

E + S —-> ES

Question 3

The rate constant k-1 describes which reaction?

Answer 3

ES —-> E + S

Question 4

The rate constant k2 describes which reaction?

Answer 4

ES —-> E + P

Question 5

Steady state conditions

Answer 5

when the rate of formation and breakdown of ES complex are equal.

Question 6

Michaelis-Menten plot

Answer 6

refer to slides

Question 7

Formula for Km

Answer 7

([Et] [S])/([ES]) - [S]

Question 8

The velocity of the catalyzed reaction at any time is

Answer 8

V = k2 [ES]

Question 9

When the enzyme is saturated with substrate so that all of it exists as ES complex, the velocity is maximum, Vmax =

Answer 9

k2 [Et]

Question 10

Km in terms of rate constants

Answer 10

(k-1 + k2) / (k1)

Question 11

What is Km?

Answer 11

is [S] that produces Vmax/2 and [S] at which half of the enzyme active sites are filled.

Question 12

Is Km independent of amount of enzyme?

Answer 12

yes

Question 13

Michaelis-Menten Equation

Answer 13

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

Question 14

Is Vmax independent of amount of enzyme?

Answer 14

No, Vmax depends on the amount of enzyme.

Question 15

Lineweaver-Burk Plot

Answer 15

1/V = (Km/Vmax)(1/S) + 1/Vmax

Question 16

Inhibitors

Answer 16

are small molecules or ions that can inhibit enzymes by binding.

Question 17

Competitive Inhibitors

Answer 17

compete with substrates for the active site.

Question 18

Non-competitive Inhibitors

Answer 18

bind to enzymes at the same time as substrates but at different binding sites.

Question 19

M-M plot for competitive inhibition

Answer 19

As the inhibition increases higher substrate is needed to overcome the inhibition.

Question 20

M-M plot for non-competitive inhibition

Answer 20

can not be overcome by increasing the substrate concentration, Vmax cannot be reached.

Question 21

LB plot how to find Km and Vmx

Answer 21

x-intercept: -1/Km

y-intercept: 1/Vmax

Question 22

LB plot for competitive inhibition

Answer 22

Vmax stays the same, Km increases.

Question 23

LB plot for non-competitive inhibition

Answer 23

Vmax decreases, Km stays the same.