Lecture II - Enzymes III - Michaelis-Menten Kinetics

Question 1

What are the three types of kinetic trends and their equations?

Answer 1

1. Linear (v = k[S]) 2. Hyperbolic (V0 = Vmax[S]/Km + [S]) 3. Sigmoidal (v = [S]n / Kd + [S]n

Question 2

What is the equation for first order kinetics and in which graph will first order kinetics have a linear line?

Answer 2

V = k[S]1 and ln[S] vs. time **1 S -Enzyme–> P**

Question 3

What is the equation for second order kinetics and in which graph will second order kinetics have a linear line?

Answer 3

v = k[S]^2 and 1/[S] vs. time 2S or Sa and Sb -Enzyme—> P

Question 4

What is the equation for zero order kinetics and in which graph will zero order kinetics have a linear line?

Answer 4

V = k[S]^0 = K and [S] vs. Time S -Enzyme—>P **unimolecular reaction** **enzyme is saturated**

Question 5

Michaelis-Menten enzymes follow what order of kinetics?

Answer 5

First - Order

Question 6

No matter what, catalysis is not a ______

Answer 6

First-Order reaction

Question 7

Michaelis-Mentin Kinetics model is a simplification of what?

Answer 7

The catalysis reaction, it basically states that initial concentrations of P are negligible so that we get a nice equation and graphs to work with.

Question 8

What is Km or Michaelis Constant?

Answer 8

[S] where reaction rate is half maximal OR half of the active sites are full

Question 9

What is Vmax or maximum velocity?

Answer 9

Maximum rate possible for a given concentration of enzyme.

Question 10

What is Kcat or Turnover number?

Answer 10

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

Question 11

What is Ks?

Answer 11

A dissociation constant for substrate binding

Question 12

What is Kcat/Km or specificity constant

Answer 12

Measure of enzyme performance by predicting the fate of E.S

Question 13

What is the Michaelis-Menten Equation?

Question 14

What are the three important laboratory conditions to remember?

Answer 14

1. [S] << Km: Vo = vmax/km * [S]
2. [S] = Km: Vo = vmax/2
3. [S] >> Km: Vo = Vmax

Question 15

A good enzyme will have a Kcat (>>/<<) than K-1 and kcat/km = k1

A poor enzyme with have a Kcat(>>/<<) than K-1 and Kcat/km = 1/km

Answer 15

1. Good enzyme Kcat >> k-1
2. Poor enzyme Kcat << k-1

Question 16

Multiple binding site enzymes can follow michaelis-mentin kinetics as long as they are?

Answer 16

Noncooperative

Question 17

This double reciprocal plot is a way to graph rates in a linear fashion?

Answer 17

Lineweaver-Burk plot

Question 18

What are reversible inhibitors and what are the three types of inhibition they can cause?

Answer 18

Reversible inhibitors use noncovalent interactions to bind.

1. Competitive
2. Noncompetitive
3. Uncompetitve

**2 and 3 are allosteric inhibitors**

Question 19

Competitve inhibiton graph looks like? what are the states of Vmax and Km?

Answer 19

Vmax is constant and Km is variable

Question 20

Noncompetitive inhibition looks like? what are the states of Vmax and Km?

Answer 20

Vmax is variable

Km is constant

Question 21

Uncompetitve inhibition looks like? What are the states of Vmax and Km?

Answer 21

Vmax is variable and Km is variable

Question 22

What are the three types of irreversible inhibitiors and what do they do?

Answer 22

1. Group - specific *lowest specificity*
2. Substrate Analogs - *high specificity*
3. Suicide inhibitors - *Very High Specificity*

They inactive enzymes