Lecture 13, Kinetics (Ford)

Question 1

List the 3 kinetic trends that are possible.

Answer 1

Linear, hyperbolic, sigmoidal

Question 2

What is the equation for a linear kinetic trend?

Answer 2

v = k[S]

Question 3

What is the equation for a hyperbolic kinetic trend?

Answer 3

v0 = (vmax*[S]) / (Km + [S])

Question 4

What is the equation for a sigmoidal kinetic trend?

Answer 4

v = [S]^n / KD + [S]^n

Question 5

How do you determine the reaction order based on the graph?

Answer 5

Linear line (k is the absolute value of the slope of the line)

Question 6

Describe the linear graph for first order kinetics.

Answer 6

ln[S] vs. time

Question 7

Describe the linear graph for second order kinetics.

Answer 7

1/[S] vs. time

Question 8

Describe the linear graph for zero order kinetics.

Answer 8

[S] vs. time

Question 9

What are the substrate-independent interpretations of a zero order reaction?

Answer 9

Unimolecular reaction and enzyme is saturated

Question 10

T or F: For a reversible reaction, the substrate is being both used and created.

Answer 10

True.

Question 11

What is the equation for a reversible reaction at equilibrium?

Answer 11

k1[S] = k-1[P]

Question 12

For a reversible reaction, how can the association and dissociation constants be redefined?

Answer 12

KA = k1/k-1
KD = 1/KA

Question 13

T or F: No matter what, catalysis is a first order reaction.

Answer 13

False. Michaelis-Menten enzymes follow first order kinetics, but not matter what, catalysis is not a first order reaction.

Question 14

How can reaction rate a catalysis be simplified if we make some assumptions?

Answer 14

E + S ← → E * S → E + P

Question 15

When reaction rate is simplified, describe the changes in concentration.

Answer 15

Linear

Question 16

T or F: [E] cannot be measured.

Answer 16

True.

Question 17

Moving toward a Michaelis-Menten equation and assuming that the binding of the substrate is at equilibrium, how can the equilibrium constant be defined?

Answer 17

KS = KD; KS = k-1/k1

Question 18

Regarding reaction rate simplification, what is the steady state assumption?

Answer 18

[S]&raquo_space; [E]

Question 19

Regarding reaction rate simplification, describe the formation of the E*S complex.

Answer 19

Formation occurs at the same rate as its loss

Question 20

What is the rate-determining step when simplifying the reaction rate?

Answer 20

k2

Question 21

Since k2 is the rate-determining step, what is the rate of product formation?

Answer 21

v0 = kcat * [E*S]

Question 22

Why can’t [E*S] be meaured?

Answer 22

Transient and unstable

Question 23

What does it mean when vmax is reached?

Answer 23

Enzyme is fully saturated; [E*S] = [E]T

Question 24

Describe the kcat of a good enzyme.

Answer 24

kcat&raquo_space; k-1; kcat/Km ~ k1

Question 25

Describe the kcat of a poor enzyme.

Answer 25

kcat << k-1; kcat/Km ~ 1/Km

Question 26

T or F: Multiple binding site enzymes can follow Michaelis-Menten kinetics, whether they are cooperative or noncooperative.

Answer 26

False. Multiple binding site enzymes can follow Michaelis-Menten kinetics, as long as they are noncooperative.

Question 27

What is the equation for a Lineweaver-Burk plot?

Answer 27

1/v0 = Km/vmax * 1/[S]0 + 1/vmax

Question 28

T or F: Inhibitors can be reversible or irreversible.

Answer 28

True.

Question 29

What kind of bonds do reversible inhibitors utilize?

Answer 29

Noncovalent interactions

Question 30

What are the types of inhibition reversible inhibitors use?

Answer 30

Competitive, noncompetitive, uncompetitve

Question 31

Which of the reversible inhibitors are allosteric?

Answer 31

Noncompetitive, uncompetitive

Question 32

Describe the vmax and Km of competitive inhibitors.

Answer 32

``` vmax = constant Km = variable ```

Question 33

Describe the vmax and Km of noncompetitive inhibitors.

Answer 33

``` vmax = variable Km = constant ```

Question 34

Describe the vmax and Km of uncompetitive inhibitors.

Answer 34

``` vmax = variable Km = variable ```

Question 35

What does the graph for a competitive inhibitor look like?

Answer 35

Chopsticks

Question 36

What does the graph for a noncompetitive inhibitor look like?

Answer 36

V

Question 37

What does the graph for a uncompetitive inhibitor look like?

Answer 37

Railroad tracks

Question 38

What do irreversible inhibitors do?

Answer 38

Inactivate enzymes

Question 39

What do group-specific irreversible inhibitors target?

Answer 39

Specific amino acid (low specificity)

Question 40

What do substrate analog irreversible inhibitors target?

Answer 40

Substrate mimic, modifies enzyme (high specificity)

Question 41

What do suicide inhibitor irreversible inhibitors target?

Answer 41

Substrate mimic, unable to form products (very high specificity)