focus chapter 7 (kinetics and enzyme regulation)

Question 1

express a simple chemical reaction using the basic chemical rate law.

Answer 1

o A —K—-> B
o V=k[A]
 A= reactant
 B= product
 K=rate constant
 V=reaction rate or velocity

Question 2

List three main assumptions of Michaelis-Menten kinetics.

Answer 2

-The steady-state assumption: [ES] is constant
-Free ligand approximation: valid as long as [E] is well below KM
-Rapid equilibrium approximation: substrate binding and dissociation occurs more rapidly than product formation

Question 3

Km

Answer 3

• the ability of an enzyme to bind the substrate
   Loosely related to the affinity of the enzyme for substrate (a dissociation constant)
   Unique for each enzyme-substrate pair
   The substrate concentration at which the reaction velocity is half-maximal

Question 4

Kcat

Answer 4

-the ability of an enzyme to catalyze a reaction
 varies for each substrate with an enzyme
 turnover number of the enzyme
 number of substrate molecules turned over to product molecules by the enzyme per unit time
 number of reaction processes (turnovers) that each active site catalyzes per unit time.

Question 5

Vmax

Answer 5

The maximum velocity of an enzymatically catalyzed reaction when the enzyme is saturated with its substrate

Question 6

catalytic efficiency (kcat/Km)

Answer 6

A large kcat/KM ratio can arise from either a large kcat or a small KM (tight binding)

Question 7

Michaelis-Menten plot

Answer 7

records the velocity of a reaction with increasing concentration of substrate

Question 8

Lineweaver-Burk plots

Answer 8

Use data from M-M experiment and generate a double reciprocal plot