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Biochem > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Enzyme that catalyzes oxidation-reduction reactions

A

Oxidoreductase

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2
Q

Enzyme that catalyzes the transfer of C-, N-, or P- containing groups

A

Transferase

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3
Q

Enzyme that catalyzes the cleavage of bonds by the addition of water

A

Hydrolase

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4
Q

Enzyme that catalyzes the cleavage of C-C, C-S, and certain C-N bonds

A

Lyase

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5
Q

Enzyme that catalyzes the racemization of optical or geometric isomers

A

Isomerase

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6
Q

Enzyme that catalyzes the formation of bonds between carbon and O, S, N coupled to hydrolysis of high energy phosphates (e.g. ATP)

A

Ligase

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7
Q

Value of the energy of reactants minus the energy of the products of a reaction

A

Free energy (delta G)

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8
Q

Enzymes accelerate rxns by lowering:

A

Activation energy

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9
Q

Enzymes don’t affect:

A

Equilibrium constant (Keq) and Free energy

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10
Q

Protease with a hydrophobic pocket for substrates Phe, Trp, tyr

A

Chymotrypsin

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11
Q

Protease with a salt bridge for substrates Lys, Arg

A

Trypsin

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12
Q

Protease with a small hydrophobic pocket for substrates Gly, Ala

A

Elastase

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13
Q

Enzyme activated by proteolytic cleavage

A

Zymogen/Proenzyme

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14
Q

Includes the apoenzyme and the required cofactors

A

Holoenzyme

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15
Q

Homologous enzymes that differ in amino acid sequence but catalyze the same reaction
May show altered kinetics and/or organ/tissue specificity

A

Isozyme

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16
Q

Small organic, non-protein molecules that are required for catalysis

A

Coenzymes

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17
Q

Many coenzymes are derived from:

A

Vitamins

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18
Q

Tightly bound coenzymes that remain tightly bound to the enzyme at all times

A

Prosthetic groups

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19
Q

Coenzymes that diffuse from one enzyme to another

A

Co-substrates

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20
Q

Coenzymes that form a covalent bond with the substrate, activating it for the reaction

A

Activation transfer coenzymes

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21
Q

Activation transfer coenzyme that activates fatty acids, acetyl CoA

A

Coenzyme A (CoA)

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22
Q

Activation transfer coenzyme that activates alpha keto acid decarboxylations (pyruvate, alpha ketoglutarate)

A

Thiamine pyrophosphate (TPP)

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23
Q

Activation transfer coenzyme that activates CO2 for carboxylation reactions

A

Biotin

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24
Q

Activation transfer coenzyme that activates many reactions involving amino groups (e.g. transamination, aminotransferase reactions)

A

Pyridoxal phosphate (PLP)

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25
Q

Redox coenzyme primarily involved in oxidative reactions

A

NAD+

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26
Q

Redox coenzyme primarily involved in reductive reactions

A

NADPH

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27
Q

Ratio of NAD+ to NADH is high or low in the cell?

A

High in the cell, favoring oxidations

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28
Q

Redox coenzyme that is reoxidized by oxygen via mitochrondrial electron transport system

A

NADH

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29
Q

Ratio of NADP+ to NADPH is high or low in the cell?

A

Low in the cell, favoring reductive biosynthesis reactions

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30
Q

Fat soluble vitamins

A

Vitamin A, D, K, E

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31
Q

Water soluble vitamin(s) non-B-complex

A

Ascorbic acid (Vitamin C)

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32
Q

Water soluble vitamins B-complex that are energy-releasing

A

Thiamine (B1)
Riboflavin (B2)
Niacin (B3)
Biotin
Pantothenic acid

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33
Q

Water soluble vitamins B-complex that are hematopoietic

A

Folic Acid
Vitamin B12

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34
Q

Water soluble vitamins B-complex that are not energy releasing or hematopoietic

A

Pyridoxine (Vitamin B6)
Pyridoxal
Pyridoxamine

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35
Q

Rare, inherited X-linked recessive metabolic disorder caused by impaired copper absorption/transport due to detective protein ATP7A

A

Menkes Disease

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36
Q

Cuproenzyme deficiency of this enzyme that leads to tortuous cerebral arteries

A

Lysyl oxidase

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37
Q

Cuproenzyme deficiency that leads to hypothermia

A

Cytochrome c oxidase

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38
Q

Cuproenzyme deficiency that leads to hypopigmentation of hair and skin pallor

A

Tyrosinase

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39
Q

Infants with Menkes disease are normal until this age, when disease manifests with developmental delays and seizures

A

2-3 months

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40
Q

Treatment for Menkes disease that normalizes plasma copper, leading to reduced epileptic discharges

A

Copper histidine

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41
Q

Acute thiamine deficiency that can be due to alcoholism

A

Beriberi heart disease

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42
Q

Term that describes how much enzyme is present

A

Activity

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43
Q

Term that describes how pure a sample of enzyme is

A

Specific activity

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44
Q

Term that describes how efficient a reaction is; catalytic speed

A

Kcat

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45
Q

Equation for Kcat

A

Kcat = Vmax / [E]

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46
Q

Enzyme concentration is directly correlated to:

A

Vmax

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47
Q

Relationship between rxn velocity and enzyme concentration

A

Linear (proportional)

48
Q

Relationship between rxn rate and substrate concentration

A

Non-linear (exhibits saturation)

49
Q

Michaelis-Menten equation

A

v = (Vmax x [S]) / [Km + [S])

50
Q

Dissociation constant between enzyme and substrate

A

Km

51
Q

Particular concentration of substrate required to achieve 1/2 Vmax

A

Km

52
Q

Tissue expression of hexokinase

A

All tissues

53
Q

Tissue expression of glucokinase

A

Liver and pancreaas

54
Q

Km of hexokinase

A

0.1 mM

55
Q

Km of glucokinase

A

10 mM

56
Q

Is hexokinase inhibited by G-6-P?

A

Yes

57
Q

Is glucokinase inhibited by G-6-P?

A

No

58
Q

Isoenzymes with different properties in the regulation of glycolysis

A

Hexokinase and Glucokinase

59
Q

Glycolysis regulator enzyme that is active at very low glucose concentration

A

Hexokinase

60
Q

Glycolysis regulator enzyme that is active even at high glucose concentrations

A

Glucokinase

61
Q

Organ that produces insulin

A

Pancreas

62
Q

Lineweaver-Burk plot x- and y-axis

A

X axis: 1/[S]
Y axis: 1/v

63
Q

Affect of Vmax and Km with:
Competitive inhibitors

A

Vmax unaffected
Apparent Km increased

64
Q

Affect of Vmax and Km with:
Noncompetitive inhibitors

A

Vmax decreased
Km unaffected

65
Q

Multisubstrate enzymes typically see what type of inhibition?

A

Noncompetitive inhibition

66
Q

Inhibitor that only binds to the enzyme after the substrate has bound

A

Uncompetitive inhibitor

67
Q

Affect of Vmax and Km with:
Uncompetitive inhibitors

A

Km and Vmax both decrease

68
Q

Affect of Vmax and Km with:
Covalent inhibitors

A

Vmax lowered (due to less active enzyme)
Km unaffected

69
Q

Organophosphates that inhibit serine hydrolases

A

Malathion, DFP, Sarin, Nerve gasses

70
Q

Serine hydrolase that is inhibited by organophospahtes

A

Acetylcholinesterase (AChE)

71
Q

Action of acetylcholinesterase

A

Hydrolyzes acetylcholine to choline then acetate, inactivating it after muscle contraction

72
Q

Affect when acetylcholinesterase is inhibited

A

Acetylcholine is not removed, and the muscle continues to contract

73
Q

Suicide inhibitors are a type of what kind of irreversible inhibitors?

A

Transition state analogs (substrate analogs)

74
Q

Suicide inhibitor that blocks the enzyme forming uric acid for gout treatment

A

Allopurinol

75
Q

Suicide inhibitor that blocks bacterial cell wall synthesis

A

Penicillin

76
Q

Types of reversible inhibitors

A

Competitive, noncompetitive, uncompetitive

77
Q

Types of irreversible inhbitors

A

Covalent, transition-state analogs

78
Q

Phosphorylation of Ser, Thr, or Tyr side chains by kinases activates and inactivates what type of enzymes?

A

Activates catabolic enzymes
Inactivates anabolic enzymes

79
Q

Type of non-covalent enzyme regulation usually involving multi-subunit enzymes, with interdependent subunits

A

Allosteric enzymes

80
Q

Shape of curve of kinetics of allosteric enzymes

A

Sigmoidal

81
Q

Affect of Vmax and Km with:
Allosteric regulation

A

May affect Vmax, but more frequency affect Km (or both)

82
Q

Allosteric modulator that is not a substrate

A

Heterotropic effector

83
Q

Allosteric modulator where the substrate may act as the allosteric effector, binding at an allosteric site as well as the active site

A

Homotropic effector

84
Q

Regulation of glycogen phosphorylase

A

Covalent (by phosphorylation of Ser, Thr side chains) and allosteric (activated by AMP)

85
Q

Aspartate transcarbamyolase and protein kinase A regulation

A

Allosteric regulation

86
Q

Positive effector of protein kinase A that binds to regulatory subunits, releasing and activating catalytic subunits

A

cAMP

87
Q

Relationship between velocity and temperature

A

V increases with temp until it hits a point; proteins frequently denature above 105 degrees F

88
Q

ALT (Ala aminotransferases) are elevated in:

A

Liver

89
Q

AST (Asp aminotransferases) are elevated in:

A

Liver, cardiac/skeletal muscle, kidney and brain

90
Q

Amylase and Lipase are elevated in:

A

Pancreas diseases

91
Q

GGT (gamma-glutamyl transferase) is elevated in:

A

Liver disease, especially biliary obstruction, alcohol excess

92
Q

ALP (alkaline phosphatase) is elevated in:

A

Bone diseases

93
Q

Acid phosphatase is elevated in:

A

Prostate cancer

94
Q

Enzymes elevated in the liver

A

ALT and AST

95
Q

Enzymes elevated in pancreas diseases

A

Amylase and Lipase

96
Q

Enzyme elevated in liver diseases and alcohol excess

A

GGT

97
Q

Enzyme elevated in bone diseases

A

ALP

98
Q

Enzyme elevated in prostate cancer

A

Acid phosphatase

99
Q

Multiple forms of an enzyme catalyzing the same reaction in the same organism, but often with different kinetics

A

Isoenzymes

100
Q

Distribution of LDH

A

In all cells

101
Q

LDH isozyme(s) highly expressed in myocardium

A

H4, H3M

102
Q

LDH isozyme(s) highly expressed in RBCs

A

H4, H3M

103
Q

LDH isozyme(s) highly expressed in skeletal muscle

A

M4

104
Q

LDH isozyme(s) highly expressed in liver

A

M4

105
Q

LDH H4 isozyme is expressed in:

A

Myocardium and RBCs

106
Q

LDH H3M isozyme is expressed in:

A

Myocardium and RBCs

107
Q

LDH M4 isozyme is expressed in:

A

Skeletal muscle and liver

108
Q

Creatine phosphokinase (CPK) isozyme found in muscle

A

MM

109
Q

Creatine phosphokinase (CPK) isozyme found in brain

A

BB

110
Q

Creatine phosphokinase (CPK) isozyme increased in myocardial infarcts

A

MB

111
Q

Enzyme elevated soon after an MI but disappears rapidly

A

CK

112
Q

Enzyme slower to appear after an MI but persists for several days

A

LDH

113
Q

Protein that arises early after an MI and persists for several days

A

Troponin

114
Q

Test to measure MB isozyme of CPK

A

Antibody test

115
Q

Test to measure Troponin

A

Specific antibody tests (Sandwich ELISA)

Biochem (21 decks)

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