Lecture 13 Flashcards

1
Q

What are the 3 ways you should graph your data in order to determine the reaction order of the reaction?

A

(the following are all Y axis values and are plotted with the X axis representing time)

[S]

ln[S]

1/[S]

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2
Q

Once you have graphed your data one of the 3 ways, which line identifies the reaction order? what value represents the slope of the line?

A

the linear line identifies the reaction order of the data

the K value is the slope of the line

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3
Q

For first order kinetics, describe y axis equation for the line that is expected to be linear and state the what V=

A

Y axis: ln[S]

v = k[S]

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4
Q

For second order kinetics, describe y axis equation for the line that is expected to be linear and state the what V=

A

Y Axis: 1/[S]

v = k[Sa][Sb]

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5
Q

For Zero order kinetics, describe y axis equation for the line that is expected to be linear and state the what V=

A

Y axis: [S]

v = k

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6
Q

For first order kinetics, state the relationship between the substrate(s) and the product(s)

A

1 S –> P

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7
Q

For second order kinetics, state the relationship between the substrate(s) and the product(s)

A

2 S –> P

2 different substrates?

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8
Q

For Zero order kinetics, state the relationship between the substrate(s) and the product(s)

A

S –> P

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9
Q

state the 2 criteria of a zero order reaction that are unique to it

A
  1. it is a unimolecular reaction

2. the enzyme is saturated

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10
Q

State the type of reversible inhibition that has a constant Vmax and a variable Km. THEN state what it’s graph looks like.

A

Competitive: forms a steeper slope that intersects with the uninhibited plot at the Y axis
(competitive chopsticks)

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11
Q

State the type of reversible inhibition that has a variable Vmax and a constant Km. THEN state what it’s graph looks like.

A

Noncompetitive: forms a steeper slope that intersects with the uninhibited plot at the x axis
(“nom nom” noncompetitive)

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12
Q

State the type of reversible inhibition that has a variable Vmax and a variable Km. THEN state what it’s graph looks like.

A

Uncompetitive: has the same slope as the uninhibited plot but does not intersect with it
(UNcompetitive is UNassociated with the slope)

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13
Q

Which of the 3 reversible inhibition types are considered to be “Allosteric inhibitors”?

A

Noncompetitive

Uncompetitive

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14
Q

what are the assumptions and conditions needed to use the michaelis-Menten equation? (3 of these)

A
  1. The binding of the substrate to the enzyme is at equilibrium
    So Ks = (K-1/K1)
  2. Since we are assuming initial rate, not enough product is present for the reverse reaction to occur
    So we can ignore the E*P species
  3. The steady state assumption: when [S] is very large, DeltaS = 0 (bc an appreciable amount of substrate is not going to be converted into product)
    So the dissociation constant (Km) = (K-1 + K2)/K1
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15
Q

Define Km in words and mathematical equations

A

Michaelis Constant

Km: the [S] or concentration of the substrate that reaches half of the maximal reaction rate for a specific reaction

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16
Q

Define Vmax in words and mathematical equations

A

Maximum velocity

Vmax: the maximum rate possible for a given concentration of enzyme

17
Q

Define Kcat in words and mathematical equations

A

Turnover number

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

18
Q

Define KS in words and mathematical equations

A

(NOT like the Kd dissociation constant for the products)

A dissociation constant for the substrate that is binding

19
Q

Define Kcat/Km in words and mathematical equations

A

Specificity constant

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

20
Q

Describe how to create a Lineweaver-Burk plot (state equation for it)

A

It is a y = mx + b style equation

y = 1/V0

m = Km/Vmax

x = 1/[S]0

b = 1/Vmax

21
Q

Describe what each data point on a lineweaver-burk plot represents

A

each data point represents an individual kinetic assay

22
Q

Describe how to determine an inhibitor mechanism from a Lineweaver-Burk plot

A

graph it 3 ways and use the linear lineweaver-burk plot to determine the order of the reaction

23
Q

What is the reaction rate (v) value of a reaction at equilibrium?

24
Q

No matter what, catalysis is a ____ ______ reaction

A

first order

25
A good enzyme would have ______ and Kcat/Km would equal what?
Kcat >> K-1 | Kcat/Km = K1 describes the enzyme-substrate complex formation
26
A bad enzyme would have ______ and Kcat/Km would equal what?
Kcat << K-1 | Kcat/KM = 1/Km describes the dissociation of the enzyme-substrate complex
27
Multiple binding site reactions CAN follow michaelis menten kinetics as long as they are _____. What type of graph would be observed if it's y axis was reaction rate and the x axis was [S] and the reaction was a multiple binding site reaction that followed michaelis menten kinetics?
Noncooperative The graph would be hyperbolic (a cooperative reaction would NOT follow michaelis menten kinetics and would yield a sigmoidal curve)
28
What is a double reciprocal plot?
a lineweaver-burk plot | Double reciprocal plot = lineweaver-burk plot
29
For the following irreversible inhibitor, state what it does and the level of specificity it has for the active site. Group-Specific:
Group-specific irreversible inhibitors target a specific AA They have a low affinity for the active site
30
For the following irreversible inhibitor, state what it does and the level of specificity it has for the active site. Substrate Analogs:
Substrate analog irreversible inhibitors modify the enzyme in such a way that the reaction can no longer form the products They have a high affinity for the active site
31
For the following irreversible inhibitor, state what it does and the level of specificity it has for the active site. Suicide Inhibitors:
Suicide inhibitor irreversible inhibitors modify the substrate in such a way that the reaction can no longer form products They have a very high affinity for the active site
32
State which 2 forms of irreversible inhibitor mechanisms employ the use of substrate mimicking.
Substrate analogs Suicide inhibitors
33
Define V(sub)0
initial velocity of a reaction
34
Define K(sub)D
dissociation constant for products in a REVERSIBLE reaction | product becomes the reactant (Ks is the dissociation constant for enzyme binding to reactants)