Enzymes and enzyme kinetics Flashcards

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1
Q

Oxidoreductases

A

Catalyze oxidation/reduction rxns

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2
Q

Transferases

A

Catalyze movement of functional groups

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3
Q

Hydrolases

A

Catalyze the breaking of compounds with water

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4
Q

Lyases

A

Catalyze the cleavage of one compound into two

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5
Q

Isomerases

A

Catalyze bond rearrangement within a molecule

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6
Q

Ligases

A

Catalyze addition or synthesis rxns

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7
Q

Km

A

Equals the [S] at 1/2 Vmax
-The Michaelis-Menton constant

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8
Q

Kcat

A

Measures the amount of substrate converted into product

(the amount CATalyzed)

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9
Q

Catalytic efficiency ratio and meaning

A

Kcat/Km

How efficient the enzyme is at converting substrate into product

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10
Q

What is enzyme cooperativity and how is it measured?

A

Cooperativity is a measure of whether or not the affinity for a ligand increases as more active sites are bound (ex: binding to one active site increases the enzymes affinity for the next active site)

Measured by Hills coefficient:
>1 positive cooperativity
=1 no cooperative binding
<1 negative cooperativity

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11
Q

Competitive inhibition:
Binding site
Vmax ____
Km ___

A

Active site
Vmax stays the same (can be outcompeted)
Km increases (affinity for S decreases, but Km is inverse)

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12
Q

Non-competitive inhibition:
Binding site
Vmax ____
Km ___

A

Bind equally well to the E+S and ES complex
Vmax decreases
Km stays the same (think of non-competitive like a special type of mixed inhibitor. Since it can bind either the E+S or ES complex, the change in Km is negligible and looks like there’s no change overall)

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13
Q

Mixed inhibition:
Binding site
Vmax ____
Km ___

A

Allosteric site of either E+S or ES complex
Vmax always decreases
Km increases if binding E+S (because S can’t bind if there’s a conformation change)
Km decreases if binding ES (because the enzyme won’t let go of the S, so it looks like it has a high affinity)

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14
Q

Uncompetitive inhibition:
Binding site
Vmax ____
Km ___

A

Allosteric site of ES only
Vmax decreases
Km decreases (E never releases S, so less product will be formed)

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15
Q

Allosteric enzymes

A

Have allosteric sites that, when bound, affect the affinity of active sites
-can turn active sites on or off by inducing a conformation change

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16
Q

Covalently modified enzyme

A

Modify enzyme by creating new bonds

Ex: glycoslyation, phosphorylation

17
Q

Zymogens control ____

A

Enzymes that otherwise would be harmful if they were never turned off
-Have a regulatory domain that can be turned on or off to make sure the enzyme doesn’t go out of control