Enzyme Kinematics Flashcards

Types of enzymes and inhibition, Vmax and Km, etc.

1
Q

Substrate

A

What enzymes interact with

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2
Q

Enzyme binding site

A

Where intermolecular interactions occur

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3
Q

Enzyme catalytic site

A

Where the reaction is catalyzed

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4
Q

Induced fit model

A

Enzyme and substrate shape affect each other; explains stabilization of the transition state

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5
Q

Ligand

A

Regulatory molecules and substrates (any substance an enzyme interacts with)

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6
Q

Orthosteric regulation

A

Elements that interact with an enzyme at its active site

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7
Q

Allosteric regulation

A

Elements that bind to an enzyme at sites other than the active site

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8
Q

Oxidoreductases

A

Catalyze redox reactions

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9
Q

Transferases

A

Transfer functional groups between molecules

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10
Q

Hydrolases

A

Catalyze hydrolysis

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11
Q

Isomerases

A

Catalyze isomerization; name often includes “mutase” suffix

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12
Q

Lyases

A

Cleave bonds using mechanisms other than hydrolysis

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13
Q

Ligases

A

Join molecules together with covalent bonds

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14
Q

Alcohol dehydrogenase

A

Type of oxidoreductase; converts alcohols to aldehydes

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15
Q

Phosphatase

A

Remove phosphate groups

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16
Q

Kinases

A

Type of transferase; add phosphate groups to acceptor molecules

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17
Q

What type of bonds do enzymes use to bind to substrates?

A

Noncovalent

18
Q

Feedback

A

Downstream product of a pathway reaches backward to regulate upstream steps

19
Q

Feed-forward regulation

A

Product helps a later step that it is not directly involved in

20
Q

Cooperativity

A

An enzyme binding one ligand makes it easier to bind the second; each subsequent ligand is easier to bind (ex: hemoglobin)

21
Q

Sigmoidal curve (S shape)

A

Curve indicating cooperativity

22
Q

Hill Coefficient

A

Indicator of cooperativity
>1 = positive cooperativity
0 = no cooperativity
<1 = negative cooperativity

23
Q

Phosphorylation

A

Covalently adding a phosphate group to a protein

24
Q

Zymogen

A

Inactive enzyme precursors

25
Cofactors
Molecules required by enzymes to function -Can be organic or inorganic
26
Coenzymes
Organic cofactor molecules (vitamins)
27
Prosthetic groups
Coenzymes that are tightly or covalently bonded to their enzymes (ex: heme)
28
Holoenzyme
Enzyme + all cofactors and coenzymes
29
Apoenzyme
Only enzyme, without addition of cofactors
30
Michaelis-Menten Model
Explains how the rate of an enzyme catalyzed reaction is dependent on the concentration of the enzyme and its substrate
31
Saturation
All enzyme molecules are occupied; reaction is at max velocity
32
Km
Substrate concentration that corresponds to 1/2 of Vmax; measure of affinity (higher = greater affinity)
33
Reaction velocity equation
(Vmax*[S]) / (Km + [S])
34
Michaelis-Menten Plot
Reaction rate as a function of substrate concentration
35
Lineweaver-Burk Plot
Double reciprocal transformation of Michaelis-Menten Plot
36
x-intercept value of Lineweaver-Burk Plot
-1/Km (higher Km = closer to origin)
37
y-intercept value of Lineweaver-Burk Plot
1/Vmax (higher Vmax = closer to origin)
38
Competitive inhibitor
Compete with the substrate for the active site -Vmax stays the same -Km increases -Steeper LBP slope
39
Noncompetitive inhibitor
Interact with the enzyme and enzyme-substrate complex allosterically (bind to both with equal affinity) -Vmax decreases -Km stays the same -Steeper LBP slope
40
Uncompetitive inhibition
Interact allosterically with the enzyme-substrate complex to prevent enzyme from converting substrate to product after substrate has already bound -Vmax decreases -Km decreases -x and y intercepts on LBP move away from origin
41
Mixed inhibition
Can bind to allosteric site on free enzyme or to enzyme-substrate complex -Vmax decreases -Varying effects on Km: -Binds free enzyme: Km increases -Binds E-S complex: Km decreases