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01 Cell > 2.09 Enzymes > Flashcards

2.09 Enzymes Flashcards

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1
Q

specialized protein catalysts that accelerate chemical reactions, used in biochemical reactions and pathways

A

Enzymes

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2
Q

Mechanism of enzymes wherein there is conformational change when the substrate binds to the enzyme’s active site

A

Induced fit (Daniel Koshland)

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3
Q

The molecule acted upon by the enzyme to form a product

A

Substrate

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4
Q

Enzymes that require a metal in their composition

A

Metalloenzymes

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5
Q

Parts of a holoenzyme

A

Protein part

Cofactor (Non-protein part)

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6
Q

Examples of Cofactors

A

Coenzymes
Prosthetic groups
Metal Ions

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7
Q

Classes of Coenzymes

A

Activation Transfer Coenzymes

Oxidation Reduction Coenzymes

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8
Q

What to look for in enzyme cofactors

A

Coenzyme
Enzyme
Chemical groups transferred
Vitamin Precursor

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9
Q

The enzyme that catalyzes the rate-limiting or committed step of a metabolic pathway

A

Regulatory enzyme

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10
Q

Intracellular locations of some important biochemical pathways

A

Mitochondria
Cytosol
Nucleus
Lysosome

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11
Q

Different structural forms of an enzyme which catalyze the same chemical reactions

A

Isoenzyme

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12
Q

Enzymes that act on the same substrate and produce the same products but exhibit differing degrees of efficiency

A

Isoenzyme

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13
Q

Six major classes of enzymes

A 
Oxidoreductases
Transferases
Hydrolases
Lyases
Lysases
Isomerases
Ligases
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14
Q

Part of the enzyme which contains amino acid side chains that participate in substrate binding and catalysis

A

Active site

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15
Q

Enzyme that transfer of electron and hydrogen atoms from donors

A

Oxidoreductases

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16
Q

Enzyme that transfers functional groups from donors to acceptors

A

Transferases

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17
Q

Enzyme that csatalyze cleavage of chemical bonds by addition of H2O, producing 2 products

A

Hydrolases

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18
Q

Enzyme that cleaves C-C, C-O, and C-N bonds by means other than hydrolysis or oxidation

A

Lyases

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19
Q

Enzyme that catalyzes a psychologically important reaction that favors the formation of a C-C bond

A

Synthase

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20
Q

Type of lyases that adds H2O to a substrate

A

Hydratase

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21
Q

Transfer of functional groups or double bonds within the same molecule

A

Isomerases

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22
Q

Enzyme that catalyzes the joining of substrates in the presence of ATP

A

Ligases

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23
Q

Characteristics of enzymes

A

Not changed in the reaction
Do not change or alter the equilibrium of the reaction
Increase reaction rates by decreasing activation energy
Highly specific
Mostly proteins in nature

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24
Q

Significance of the Km

A

1) Substrate concentration at which half the active sites of the enzyme are filled up
2) Inverse measure of the affinity of the substrate for the enzyme

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25
Reversible inhibitions of enzymatic reactions
Competitive Non competitive Uncompetitive
26
Type of inhibition wherein the inhibitor binds specifically at the active or catalytic site, where it competes with the substrate for binding
Competitive inhibition
27
Type of inhibition wherein the inhibitor binds a substance other than at the active or catalytic site
Non competitive
28
Type of inhibition wherein the inhibitor binds only to ES complexes at locations other than the catalytic site, modifying enzyme structure, making the inhibitor binding site available
Uncompetitive inhibition
29
Type of inhibition wherein the inhibition is reversed by increasing substrate concentration
Competitive inhibition
30
Type of inhibitor Vmx: decrease proportionately to inhibitor concentration Km: unchange
Non competitive inhibitor
31
Type of inhibitor Vmax: decrease Km: decrease
Uncompetitive inhibitor
32
Type of inhibitor Vmax: unchange Km: increase
Competitive inhibitor
33
Enzymes following Michaelis-Menten kinetics show (linear/hyperbolic/sigmoid) curve.
Hyperbolic
34
Allosteric enzymes exhibit (linear/hyperbolic/sigmoid) curve
Sigmoid
35
Methods of regulating enzyme activity
``` Feedback inhibition Allosteric (non-covalent) modification Covalent modification Zymogen activation Induction or repression of enzyme synthesis ```
36
Binding of modulator to allosteric site, which causes a conformational change in the regulatory enzyme, alters the activity of the enzyme
Allosteric modification
37
(Low/High) Activity | Dephosphorylating Acetyl Coa Carboxylase
High
38
(Low/High) Activity | Phosphorylating Glycogen synthase
Low
39
(Low/High) Activity | Phosphorylating Pyruvate dehydrogenase
Low
40
(Low/High) Activity | Dephosphorylating HMG CoA reductase
High
41
(Low/High) Activity | Phosphorylating Glycogen phosphorylase
High
42
(Low/High) Activity | Dephosphorylating Citrate lyase
Low
43
(Low/High) Activity | Dephosphorylating Phosphorylase b kinase
Low
44
(Low/High) Activity | Phosphorylating HMG CoA reductase kinase
High
45
(Low/High) Activity | Dephosphorylating HMG CoA reductase kinase
Low
46
(Low/High) Activity | Phosphorylating Phosphorylase b kinase
High
47
(Low/High) Activity | Phosphorylating Citrate lyase
High
48
(Low/High) Activity | Dephosphorylating glycogen phosphorylase
Low
49
(Low/High) Activity | Phosphorylasing HMG CoA reductase
Low
50
(Low/High) Activity | Dephosphorylating pyruvate dehydrogenase
High
51
(Low/High) Activity | Dephosphorylating glycogen synthase
High
52
(Low/High) Activity | Phosphorylating Acetyl CoA carboxylase
Low
53
Factors affecting enzyme activity
Temperature pH Substrate concentration Co-factors
54
As the temperature increases (until the optimum temperature is reached), the reaction velocity or the enzyme activity (increases/decreases)
Increases
55
Beyond the optimum temperature, the reaction velocity/enzyme activity (increases/decreases) as the temperature increases
Decreases
56
Increasing the pH value will (increase/decrease) the reaction rate
Increase | But, beyond the optimum pH, the reaction rate will decrease
57
Cofactors (chlorides, bromides, iodides) ___ the rate of enzyme-catalyzed reactions
Increase
58
As the substrate concentration increases, the reaction velocity (increases/decreases)
Increases | Up to a certain point
59
Substate concentration at which half of the active sites of the enzyme are filled up
Km
60
The lower the Km, the ___ is the affinity
Higher
61
The higher the Km, the ___ is the affinity
Lower
62
Models of enzyme-substrate complex
Lock and Key Model | Induced Fit Model

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