Chapter 12

Question 1

What is reaction velocity (v)?

Answer 1

Rate of change from reactants to products with respect to time

Question 2

What is the rate constant (k)?

Answer 2

Describes how a reaction is dependent on the concentration of reactant/substrate

Question 3

What is the equation for reaction velocity (v)?

Answer 3

v = k[A]

Question 4

What do the enzyme and substrate react to form?

Answer 4

Michaelis (ES) Complex

Question 5

What are the three assumptions of enzyme kinetics?

Answer 5

Initial Velocity Assumption
Equilibrium Assumption
Steady State Assumption

Question 6

What does the initial velocity assumption say?

Answer 6

Before a build-up of P then the reverse reaction is negligible (ignore P + E -> ES)

Question 7

What does the equilibrium assumption say?

Answer 7

The first step of the reaction reaches equilibrium before the production of products

Question 8

What is the equation for the dissociation constant (Ks)?

Answer 8

Ks = [E][S] / [ES]

Question 9

What does the steady state assumption say?

Answer 9

The rate of ES formation equals the rate of ES consumption ([ES] = constant)

Question 10

What is the Michaelis-Menten equation?

Answer 10

Vo = Vmax[S] / Km + [S]

Question 11

What is Vmax?

Answer 11

The theoretical maximum rate; would require that all enzyme molecules be bound to the substrate

Question 12

What is Km?

Answer 12

Substrate concentration that reaches half maximum velocity

Question 13

What does a small Km mean?

Answer 13

The substrate has a high affinity for the enzyme

Question 14

What does a large Km mean?

Answer 14

The substrate has a low affinity for the enzyme

Question 15

What is the equation for Km?

Answer 15

k-1 + k2 / k1

Question 16

What is Kcat?

Answer 16

Turnover number; number of substrate molecules converted to product per enzyme molecule per unit of time

Question 17

What is the equation for Kcat?

Answer 17

Vmax / [E]t

Question 18

What is the formula for catalytic efficiency?

Answer 18

Vo = (Kcat/Km) [E][S]

Question 19

What is maximum catalytic efficiency?

Answer 19

10^9 m^-1 s^-1

Question 20

What limits catalytic efficiency?

Answer 20

Diffusion limit

Question 21

What is the diffusion limit?

Answer 21

How quickly the ES complex will get together

Question 22

What is the purpose of a lineweaver-burk plot?

Answer 22

Plot Michaelis-Menten on a linear plot

Question 23

What are the three types of enzyme inhibition?

Answer 23

Competitive
Uncompetitive
Non-competitive

Question 24

What is competitive inhibition?

Answer 24

Inhibitor competes with substrate for binding site

Question 25

What does the Lineweaver-Burk graph look like for competitive inhibition?

Answer 25

Same y-intercept, different slopes

Question 26

What is uncompetitive inhibition?

Answer 26

Inhibitor binds to ES complex

Question 27

What does the Lineweaver-Burk graph look like for uncompetitive inhibition?

Answer 27

Same slopes, different y-intercepts

Question 28

What is noncompetitive inhibition?

Answer 28

Combination of competitive and uncompetitive inhibition; inhibitor binds at an exosite whether or not substrate is bound

Question 29

For mixed inhibition what does it mean is Ki = Ki`?

Answer 29

Equal affinity

Question 30

For mixed inhibition what does it mean is Ki < Ki`?

Answer 30

More affinity for the enzyme

Question 31

For mixed inhibition what does it mean is Ki > Ki`?

Answer 31

More affinity for ES complex

Question 32

What is an ordered single-displacement reaction?

Answer 32

Bimolecular reaction in which the leading substrate must bind first followed by an ordered release of product

Question 33

What is a random single-displacement reaction?

Answer 33

Bimolecular reaction in which either substrate may bind first

Question 34

What is a double displacement reaction?

Answer 34

Ping-pong reaction
Bimolecular reaction in which the product of the first reaction is released prior to reaction with second substrate