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Enzymology Introduction Flashcards

(75 cards)

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1
Q

How enzymes act in reactions

A

Lower activation energy for reactions

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2
Q

Where enzymes are found

A

In all body tissues, appear in serum after cellular injury

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3
Q

Enzyme specificity - absolute specificity

A

Combines with one substrate and catalyzes one reaction

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4
Q

Enzyme specificity - group specificity

A

Combines with substrates containing a particular chemical group

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5
Q

Enzyme specificity - bond or reaction specificity

A

Forms or breaks one type of covalent bond

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6
Q

Enzyme specificity - stereoisomeric/geometric specificity

A

Combines with only one optical or geometric isomer

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7
Q

Main function of enzymes

A

Accelerates biochemical reactions; biological catalyst

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8
Q

Enzyme involvement in reactions

A

Enzyme is not a direct participant and does not change

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9
Q

Binding sites of enzymes

A

Active site (main), Allosteric site (for cofactors)

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10
Q

Role of cofactors

A

Activate enzyme; reaction won’t proceed without them

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11
Q

Types of cofactors

A

Activator (inorganic), Coenzyme (organic)

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12
Q

Apoenzyme + Cofactor

A

Holoenzyme

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13
Q

Inactive form of enzyme

A

Proenzymes/Zymogens

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14
Q

Common enzymes with proenzymes

A

Hydrolases

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15
Q

Enzyme classification EC code 1

A

Oxidoreductases - Redox reaction (hydrogen and oxygen)

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16
Q

Function of oxidoreductases

A

Addition of hydrogen and oxygen; oxidation removes hydrogen, adding oxygen replaces hydrogen

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17
Q

Examples of oxidoreductases

A

Dehydrogenase, oxidase, hydrogenase, oxygenase

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18
Q

Enzyme classification EC code 2

A

Transferases - Transfers functional group (not H and O)

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19
Q

Function of transferases

A

Transfers functional groups like carbohydrate, phosphate, hydroxy group, amino acid

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20
Q

Example of transferase reaction

A

Creatine kinase + ATP <-> CP + ADP

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21
Q

Examples of transferases

A

Transferase, kinase (phosphate extraction from ATP), phosphorylase (transfers phosphate)

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22
Q

Enzyme classification EC code 3

A

Hydrolases - Removes functional group with water

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23
Q

Examples of hydrolases

A

Amylase (destroys glycosidic bonds), Lipase (destroys ester bonds), Trypsin/Chymotrypsin (destroys peptide bonds)

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24
Q

Enzyme classification EC code 4

A

Lyases - Removes functional group without water (H2O)

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25
Function of lyases
Products have double bond
26
Examples of lyases
Aldolase, decarboxylase
27
Enzyme classification EC code 5
Isomerases - Converts isomer from one orientation to another
28
Example of isomerase reaction
D to L orientation of glucose
29
Identification of isomerases
Isomerase in name; Example - triose phosphate isomerase
30
Enzyme classification EC code 6
Ligases - Bond formation coupled with ATP hydrolysis
31
Example of ligase
Glutathione synthetase
32
Enzyme kinetics concept
Substrate needs specific energy to proceed with a reaction, called activation energy
33
Enzyme's role in reaction
Enzyme reduces energy barrier, accelerates reaction
34
Equilibrium in enzyme kinetics
Same result, faster reaction
35
Effect of heat on enzyme reactions
Heat accelerates reactions by increasing molecular movement
36
Enzyme kinetics reaction mechanism
Enzyme + Substrate <-> ES <-> Product + Enzyme (free again)
37
Zero order kinetics
Enzyme < Substrate, rate is constant, enzyme becomes rate-limiting when active site is saturated
38
First order kinetics
Enzyme > Substrate, rate is dependent on substrate concentration, increased substrate increases enzyme-substrate complex
39
Rate limiting component in zero order kinetics
Enzyme
40
Rate limiting component in first order kinetics
Substrate
41
Inhibitor type same structure as substrate, binds to active site, reversible
Competitive inhibitor:
42
Inhibitor type Binds to enzyme (not active site), reversible, may destroy structure
Non-competitive inhibitor:
43
Inhibitor type Binds to ES complex, increasing substrate concentration, no product formation
Uncompetitive inhibitor:
44
Inhibitor type can bind to either substrate or enzyme
Mixed inhibitor:
45
Michaelis-Menten equation
v = Vmax (S) / Km + (S)
46
Lineweaver-Burke plot
Double reciprocal plot of Michaelis-Menten equation: y = mx + b
47
Fixed-time/End point measurement
One-time measurement with stop solution (weak acid)
48
Kinetic/Continuous measurement
Multiple measurements, checks actual activity and monitors linearity
49
Measurement unit for enzyme activity
IU: Amount of enzyme that catalyzes 1 umol of substrate
50
Measurement unit for enzyme concentration
IU/L
51
SI unit for enzyme activity
Katal: Number of moles per second (mol/sec)
52
Conversion between IU and Katal
1 IU = 17 katals
53
Conventional unit for enzyme activity
IU: Amount of enzyme that catalyzes 1 umol of substrate per minute
54
SI unit for enzyme activity
Katal: Amount of enzyme that catalyzes 1 mol of substrate per second
55
Conversion between IU and nkat
1 IU = 0.0161 ukat or 16.7 (17) nkat
56
Conversion between IU and kat
1 kat = 6 x 10^7 IU
57
Reactants combined, reaction proceeds for set time, reaction stopped, amount of reaction measured
Fixed-time endpoint method
58
Multiple measurements of absorbance over time using a spectrophotometer
Continuous-monitoring kinetic method
59
Factor affecting enzymatic reaction, pH range for most reactions
7.0-8.0 (except ACP: 4.5, ALP: 9-10)
60
Effect of temperature on enzymatic reaction rate
Rate doubles for every 10°C increase
61
Temperature range for denaturation in enzymatic reactions
40-50°C
62
Incubation temperature deviation in enzyme assays
±0.1°C
63
Definition of cofactors
Nonprotein entities that bind to enzymes for reactions
64
Activators as cofactors
Inorganic, metallic or non-metallic ions (e.g. Zn, Ca, Mg, Cl)
65
Definition of coenzymes
Organic substances, serve as second substrates in enzymatic reactions
66
Coenzymes bound tightly to enzymes
Prosthetic groups
67
Example of coenzyme
NAD(P) for dehydrogenases, Pyridoxal PO4 for AST, ALT
68
Effect of adding substrate in competitive inhibitor
Increased substrate reverses inhibition
69
Effect of adding substrate in non-competitive inhibitor
No effect
70
Effect of adding substrate in uncompetitive inhibitor
Increases inhibition
71
Lineweaver-Burk plot in competitive inhibitor
Same Cmax, increased Km (rightward shift)
72
Lineweaver-Burk plot in non-competitive inhibitor
Decreased Vmax, same Km
73
Lineweaver-Burk plot in uncompetitive inhibitor
Decreased Vmax, decreased Km
74
Macroenzyme definition
High-molecular-mass forms of serum enzymes bound to immunoglobulin or non-immunoglobulin substance
75
Examples of enzymes with macroforms
CK, LD, ALT, AST, GGT, ACP, ALP, AMS, LPS

Clinical Chemistry (43 decks)

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