Enzyme Kinetics

Question 1

Stages of Michaelis Menten Mechanism

Answer 1

Bimolecular formation of complex = k1
Complex to reactants = k1’
Splitting complex with formation of products = k2

Question 2

How to calculate [E]

Answer 2

[E] = conc of free enzyme
Generally only know added conc [E]0
[E] = [E]0 - [ES]

Question 3

Km

Answer 3

Michaelis Menten constant

Question 4

Small Km

Answer 4

Strong ES binding to small [S] needed for effective conversion = good enzyme

Question 5

Large Km

Answer 5

Weak ES binding = large [S] needed for effective conversion = poor enzyme

Question 6

Kcat

Answer 6

Max number of S molecules a single E molecule can convert per unit time = k2

Question 7

Vmax

Answer 7

K2[E]0

Question 8

Catalytic efficiency, η

Answer 8

Combines desirable effect of small Km and large kcat
K2 involved in both so can’t increase η indefinitely

Question 9

Max η

Answer 9

Rate constant for formation of ES, cannot me larger than k1

Question 10

Lineweaver-Burk plot

Answer 10

Inverted Michaelis Menten equation gives straight line graph

Question 11

Competitive inhibition

Answer 11

Inhibitor (I) bonds irreversibly to active site, prevents S binding
Vmax unchanged and Km increases

Question 12

Non-competitive inhibition

Answer 12

Inhibitor binds at remote site, doesn’t effect binding of S but effects production of P, [I] doesn’t effect formation of [ES] = Km unchanged

Question 13

Km meaning

Answer 13

Substrate concentration where Vmax = 50%