Lecture 9.24.14 (Ch.8 Enzyme Kinetics)

Question 1

Velocity of a reaction?

Answer 1

the quantity of S that disappear as P appear in a specific time

Question 2

Equation for V?

Answer 2

V=k[S]

Question 3

Second Order

Answer 3

keep 1 S at high concentrations & constant, while the other S is varied concentrations
(make look like its first order)

Question 4

pseudo First Order

Answer 4

Second order that’s made to look like first order

Question 5

Steady State Assumption

Answer 5

the more ES added the faster they will dissociate
therefore when the reaction is first started, there is a build up of [ES], but then [ES] becomes a steady state (constant)
[S] decrease while [P] increase, but the ES is the same

Question 6

Vmax?

Answer 6

the theoretical maximal rate of reaction that is never reached

Question 7

How can Vmax be reached?

Answer 7

require that ALL enzymes be tightly bound to substrate

Question 8

Km?

Answer 8

the [S] at 1/2 Vmax
an estimate of the equilibrium constant for S binding to E (measure of the [S] required for effective catalysis to occur)

Question 9

What does a small Km mean? high Km?

Answer 9

small: tight binding (better affinity)
high: weak binding

Question 10

Kcat?

Answer 10

turn over # (how good E is at making P)
incorporates the rate constants for all the reactions between ES and E + P and gives a direct measure of the catalytic production of product under optimum conditions (saturated enzyme).

Question 11

Kcat equation

Answer 11

Kcat=K2=Vmax/Etotal