Lecture 13 - Enzyme Kinetics

Question 1

Reaction order when ln[S] is linear.

Answer 1

First order kinetics

Question 2

Reaction order when 1/[S] is linear.

Answer 2

Second order kinetics

Question 3

Reaction order when [S] is linear.

Answer 3

Zero order kinetics

Question 4

Why would substrate be independent of enzyme (i.e. what explains zero order kinetics)?

Answer 4

Unimolecular reaction or enzyme is saturated

Question 5

Variable, [S] where reaction rate is half maximal OR half of the active sites are full

Answer 5

K_m, Michaelis Constant

Question 6

Variable, maximum rate possible for a given concentration of enzyme.

Answer 6

V_man, Maximum velocity

Question 7

Variable, number of substrate molecules converted per active site pet time (first order rate constant).

Answer 7

k_cat, Turnover number

Question 8

Variable, a dissociation constant for substrate binding.

Answer 8

K_S

Question 9

Variable, measure of enzyme performance by predicting the fate of E*S.

Answer 9

k_cat/K_m, Specificity constant

Question 10

Assumptions of Michaelis-Menten equation.

Answer 10

Binding of substrate is at equilibrium allowing us to define an equilibrium constant and steady state (i.e. [S] >> [E], change in S = 0)

Question 11

Equation, Michaelis-Menten

Answer 11

Question 12

Lab conditions where…

Answer 12

[S] < Km

Question 13

Lab conditions where…

Answer 13

[S] = K_m

Question 14

Lab conditions where…

Answer 14

[S] >> K_m

Question 15

Enzyme is […] when k_cat >> k_-1 and k_cat/K_m ~ k₁

Answer 15

Good

Question 16

Enzyme is […] when k_cat << k_-1 and k_cat/K_m ~ 1/K_m

Answer 16

Poor

Question 17

Multiple binding site enzymes can follow Michaelis-Mentin kinetics, as long as they are […].

Answer 17

Noncooperative

Question 18

Slope of Linewaever-Burk plot.

Answer 18

K_M/V_max

Question 19

Y-intercept of Lineweaver-Burk plot.

Answer 19

1/V_max

Question 20

X-intercept of Lineweaver-Burk plot.

Answer 20

-1/K_M

Question 21

Competitive inhibition: v_max = […] and K_m = […].

Answer 21

Constant; Variable

Question 22

Noncompetitive inhibition: v_max = […] and K_m = […].

Answer 22

Variable; Constant

Question 23

Uncompetitive inhibition: v_max = […] and K_m = […].

Answer 23

Variable; Variable

Question 24

Inhibition depicted

Answer 24

Noncompetitive inhibition

Question 25

Inhibition depicted.

Answer 25

Uncompetitive inhibition

Question 26

Irreversible inhibitor, targets a specific amino acid.

Answer 26

Group-specific

Question 27

Irreversible inhibitor, substrate mimic, modifies enzymes.

Answer 27

Substrate analogs

Question 28

Irreversible inhibitor, modified substrate so is unable to form products.

Answer 28

Suicide inhibitors

Question 29

Group-specific irreversible inhibition has […] affinity.

Answer 29

Low

Question 30

Substrate analogs irreversible inhibition has […] affinity.

Answer 30

High

Question 31

Suicide inhibitors irreversible inhibition has […] affinity.

Answer 31

Very high