Lecture 13- Kinetics

Question 1

Km

Answer 1

Michaelis constant; [S] where rxn rate is half maximal OR half of the active sites are full

Question 2

vmax

Answer 2

Maximum velocity; Maximum rate possible for a given concentration of enzyme

Question 3

Kcat

Answer 3

Turnover number; Number of substrate molecules converted per active site per time (first order rate constant)

Question 4

Ks

Answer 4

A dissociation constant for substrate binding

Question 5

Kcat/Km

Answer 5

Specificity constant; Measure of enzyme performance by predicting the fate of ES

Question 6

-1/Km

Answer 6

x-intercept

Question 7

1/vmax

Answer 7

y-intercept

Question 8

Reversible inhibitors

Answer 8

1. Competitive
2. Non-competitive (allosteric)
3. Uncompetitive (allosteric)

Question 9

Competitive inhibition

Answer 9

vmax is constant

Km is a variable

Question 10

Non-competitive inhibition

Answer 10

vmax is variable

Km is constant

Question 11

Uncompetitive inhibition

Answer 11

vmax is variable

Km is variable

Question 12

Irreversible inhibitors (inactive enzymes)

Answer 12

1. Group-specific
2. Substrate analogs
3. Suicide inhibitors

Question 13

Group-specific

Answer 13

• Targets a specific AA

- Specificity for active site: Low

Question 14

Substrate analogs

Answer 14

• Substrate mimic, modifies enzyme

- Specificity for active site: High

Question 15

Suicide inhibitors

Answer 15

• Modified substrate so is unable to form products

- Specificity for active site: Very high

Question 16

LO#1: Lab conditions to remember**

Answer 16

1. [S]<>Km

Question 17

[S]<

Answer 17

vo~ ((vmax/km)([S]))

Question 18

[S]=Km

Answer 18

vo= vmax/2

Question 19

[S]»Km

Answer 19

vo=vmax

Question 20

Good enzyme

Answer 20

kcat»k-1; kcat/Km~ K1*

remember ~k1

Question 21

Bad enzyme

Answer 21

kcat<