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MTAP CC2 > Clinical enzymology > Flashcards

Clinical enzymology Flashcards

1
Q

Examples of Oxidoreductases

A

LDH, G6PD, GLDH, MDH

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2
Q

Examples of Transferases

A

AST, ALT, CK, PK, GGT

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3
Q

An enzyme also called SGOT

A

AST (aspartate aminotransferase)

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4
Q

SGOT stands for

A

serum glutamic-oxaloacetic transaminase

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5
Q

Also known as SGPT

A

ALT (alanine aminotransferase)

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6
Q

SGPT stands for

A

Serum glutamic pyruvic transaminase

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7
Q

Examples of hydrolases

A

ALP, ACP, Amylase, lipase, chymotrypsin, elastase, cholinesterases, 5’ nucleotidase

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8
Q

Ex of Lyases

A

aldolase

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9
Q

ex. of Isomerases

A

Triose phosphate isomerase

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10
Q

Ex. of Ligases

A

Glutathione synthetase

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11
Q

The reaction of Oxidoreductases/Dehydrogenases

A

Oxidation-reduction

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12
Q

The reaction catalyzed by Transferases

A

Transfer of functional groups

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13
Q

The reaction catalysed by Hydrolases

A

Hydrolysis

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14
Q

The reaction catalyzed by Lyases

A

Removal of groups to form double bonds

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15
Q

The reaction catalyzed by Isomerases

A

Interconversion of isomers

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16
Q

The reaction catalyzed by Ligases

A

Bond formation coupled with ATP hydrolysis

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17
Q

describes the rate of catalysis of the enzyme at some particular substrate concentration.

A

Michaelis-Menten equation

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18
Q

Double reciprocal of Michaelis-Menten equation

A

Lineweaver-Burk equations

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19
Q

What is a first-order kinetics?

A
  • Where enzyme concentration exceeds substrate
  • More substrate, faster the reaction
  • There is continuous increase in velocity as more substrate is added or bound to an enzyme up too a certain point
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20
Q

What is zero-order kinetics?

A
  • No further increase in velocity but the reaction continues; all active sites have been occupied
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21
Q

True or False: Measurement of enzyme is based on its activity and not in concentration.

A

TRUE

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22
Q

a method of measurement where reaction is usually stopped by inactivating the enzyme with weak acid

A

Fixed-time/endpoint

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23
Q

A method of measurement where multiple measurements of absorbance change as a function of time.

A

Continuous-monitoring/Kinetic

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24
Q

A unit of measure for the amount of enzyme that catalyzes the reaction of 1 umol of substrate per minute

A

IU (international unit)

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25
Q

a unit of measurement for the amount of enzyme that catalyzes the reaction of 1 mol of substrate per second.

A

Katal

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26
Q

how many Katal are there in 1 IU

A

17 nanokatal or 0.0167 microkatal

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27
Q

In which pH range do most reactions occur

A

pH 7-8, except ACP and ALP

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28
Q

The denaturation point of enzymatic reactions is…

A

40-50 degree Celsius

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29
Q

A factor that affect enzymatic reactions that must bind to particular enzymes before a reaction occurs

A

Cofactors

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30
Q

Are inorganic cofactors

A

Activators

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31
Q

Are organic cofactors

A

Coenzymes

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32
Q

What are the three types of enzyme inhibitors?

A

competitive, non-competitive, uncompetitive

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33
Q

Inhibitor that binds to the active site

A

Competitive inhibitor

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34
Q

An inhibitor that binds to site other than the active site (allosteric site)

A

Non-competitive inhibitor

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35
Q

An inhibitor that binds to the enzyme-substrate complex

A

Uncompetitive inhiitor

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36
Q

High-molecular mass forms of the serum enzymes that can be bound to Immunoglobulin and non-immunoglobulin

A

Macroenzymes

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37
Q

Which tissues is CK found?

A

brain, heart, skeletal muscles

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38
Q

Enumerate the CK Typical Isoenzymes

A

CK-BB (CK 1), CK-MB (CK 2), CK-MM (CK 3)

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39
Q

enumerate CK Atypical Isoenzymes

A

MI, Macro-CK

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40
Q

CK Isoenzyme that is elevated in CNS damage, tumors, presence of macro-CK

A

CK-BB

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41
Q

A CK isoenzyme present in significant amounts in cardiac tissue

A

CK-MB

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42
Q

A CK isoenzyme present in striated muscle and normal serum

A

CK-MM

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43
Q

The only CK isoenzyme that is a cathode

A

MI (Mitochondrial CK)

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44
Q

What are the methods for CK determination called?

A

Tanzer-Gilvarg and Oliver-rosalki

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45
Q

Which CK method is a forward reaction?

A

Tanzer-Gilvarg

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46
Q

Which CK method is a reverse reaction?

A

Oliver-Rosalki

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47
Q

Rf values for Total CK

A

Male: 15-160 U/L (37oC)
Female: 15-130 U/L (37oC)

48
Q

Which sample is used in CK determination?

A

Heparinized plasma or serum

49
Q

True or False: Hemolysis falsely decreases CK result

A

False

50
Q

Tissue sources of Lactate Dehydrogenase

A

Heart, RBCs, renal cortex, lungs, liver, skeletal muscle

51
Q

LD isoenzyme most abundant in the heart

A

LD-1 and LD-2

52
Q

LD isotype predominant in the lungs

A

LD-3

53
Q

LD isotype predominant in the liver and skeletal muscles

A

LD-4 and LD-5

54
Q

The most labile among LD isotypes

A

LD-5

55
Q

At what temperature is LD required to be stored?

A

25oC

56
Q

Forward reaction for LD determination is called…

A

Wacker method

57
Q

Reverse reaction for LD determination is called…

A

Wroblewski-Ladue method

58
Q

Rf value for LD

A

100-225 U/L (37oC)

59
Q

The three enzymatic myocardial infarction markers

A

CK, AST, LD

60
Q

True or False: CK peaks at 48-72 hours in cases of MI

A

False

61
Q

True or False: AST normalizes in 4-5 days in MI

A

True

62
Q

True or False: LD starts to increase at 12-24 hours in MI

A

True

63
Q

In MI, LD value normalizes in___.

A

10 days

64
Q

Tissue sources of AST/SGOT

A

liver, heart, skeletal muscles

65
Q

Tissue sources of ALT/SGPT

A

liver

66
Q

Diagnostic significance of ALT

A

Acute hepatocellular disorders

67
Q

Diagnostic significance of AST in >5x/pronounced elevation

A

acute hepatocellular disorders
circulatory collapse
myocardial infarction

68
Q

Diagnostic significance of AST in 3-5x/moderate elevation

A 
Muscular dystrophy
Hepatic tumor
biliary obstruction
Congestive Heart Failure
Cardiac arrhythmia
69
Q

diagnostic significance of AST in <3x/ slight elevation

A

Cirrhosis, pericarditis, pulmonary infarction, cerebrovascular accident

70
Q

An isoenzyme elevated in extensive necrotic damage especially in alcoholic hepatitis or fulminant hepatic failure

A

Mitochondrial AST

71
Q

True or False: AST has a higher half-life than ALT

A

False

72
Q

An AST isoenzyme that is routinely determined in the laboratory

A

Cytoplasmic AST

73
Q

What type of method is Reitman-Frankel?

A

Colorimetric-Spectrophotometric assay

74
Q

Reagents used in Reitman-Frankel

A

2,4-dinitrophenylhydrazine (color developer)

0.4 N NaOH (color intensifier)

75
Q

Reitman-Frankel resulting color

A

brown, blue

76
Q

AST determination method based on the Karmen method

A

Coupled Enzymatic Reaction

77
Q

RF value for AST and ALT

A

AST: 5-35 U/L
ALT: 7-45 U/L

78
Q

Tissue sources of ALP

A

liver, bone, placenta, intestine

79
Q

Diagnostic significance of ALP in pronounced elevation

A 
bile duct obstruction
biliary cirrhosis
Paget's disease (highest elevation)
Osteogenic sarcoma
Hyperparathyroidism
80
Q

Diagnostic significance of ALP in moderate elevation

A 
Granulomatous or infiltrative disease
Infectious mononucleosis
Metastatic bone tumors
Rickets
Osteomalacia
81
Q

Diagnostic significance of ALP in slight elevation

A 
Viral hepatitis
Cirrhosis
Healing bone fractures
Growing children
Pregnancy due to placental isoenzyme
82
Q

Isoenzyme whose presence in serum depends in the blood group and secretor status of the individual; bound by A erythrocytes; level increases after consumption of fatty meal

A

Intestinal ALP

83
Q

True of False: Increase in pH falsely decrease ALP activity

A

False (As Co2 escapes, pH increases which may falsely increase ALP)

84
Q

Reference for ALP determination

A

Bowers-McComb

85
Q

What does the Bowers-McComb test utilize

A

PNPP (para-nitrophenyl phosphate)

86
Q

Color result in Bowers-McComb

A

Yellow

87
Q

Rf value for ALP

A

30-90 U/L

88
Q

Tissue sources for amylase

A

pancreas, salivary glands

89
Q

Tissue source/s for lipase

A

pancreas

90
Q

Diagnostic significance for Amylase

A

Acute pancreatitis, mumps, parotitis, macroamylasemia

91
Q

Diagnostic significance for Lipase

A

Acute pancreatitis

92
Q

Isoenzymes for Amylase

A

Pancreatic AMS

Salivary AMS

93
Q

Isoenzymes for lipase

A

None

94
Q

Most specific enzyme in pancreatitis

A

Lipase

95
Q

Bonus

A

In Amylase determination, lipemic samples must be avoided

Pain relievers should not be consumed, this may cause falsely increased results

96
Q

[Amylase determination] Decrease in color of starch-iodine complex

A

Amyloclastic method

97
Q

[Amylase determination] Classic reference method reported in Somogyi units

A

Saccharogenic method

98
Q

[Amylase determination] Increase in color intensity of soluble dye-substrate solution

A

Chromogenic method

99
Q

[Amylase determination] Commonly used, increase in absorbance of NADH at 340 nm

A

Coupled-Enzymatic/Continuous-monitoring method

100
Q

Rf values for Amylase

A

Serum: 25-130 U/L
Urine: 1-15 U/hour

101
Q

[Lipase determination] A method that uses olive oil as a substrate

A

Cherry-Crandall method

102
Q

[Lipase determination] Measures rate of clearing as fats are hydrolyzed by LPS

A

Turbidimetric method

103
Q

[Lipase determination] Based on coupled reactions with peroxidase or glycerol kinase

A

Colorimetric method

104
Q

Rf value for Lipase

A

0-1.0 U/mL (<38 units/L)

105
Q

Used to identify the source of elevated ALP in hepatobiliary disorders, alcoholic liver disease, microsomal induction by drugs and alcohol

A

GGT

106
Q

Used to identify the source of ALP in Intrahepatic cholestasis

A

5’ NT

107
Q

Sources include prostate (richest) and RBCs
Resolution of rape cases
screen prostatic carcinoma; replaced by PSA
Traditional determination; Roy Method

A

ACP

108
Q

Drug-induced hemolytic anemia;
Exacerbated by food that contain oxidative
metabolites, producing oxidative stress to
RBCs
Clinically significant if deficient in RBCs

A

G6PD

109
Q 
Normally high in plasma
Pesticide poisoning reduces PChE
Organophosphate and carbamate poisoning
Liver disease due to decrease synthesis
Genetic variants resulting in abnormal
response to muscle relaxants
Clinically significant if deficient in serum
A

PChE (Pseudocholinesterase enzyme)

110
Q

Increased in skeletal muscle disorders

A

Aldolase

111
Q

Blood pressure regulation

A

ACE

112
Q

Hemolytic anemia

A

PK

113
Q

Acute pancreatitis: increased
Chronic pancreatic insufficiency: decreased
Clinically significant if deficient in serum

A

Trypsin

114
Q

Associated with pancreatic insufficiency
Correlated w/ fecal fats & muscle fiber in
stool
Clinically significant if deficient in serum

A

Chymotrypsin/Elastase 1

115
Q

Acute myocardial infarction

But not used as a marker for AMI

A

Glycogen phosphorylase

116
Q

Bonus

A

↑ ALP, ↑ GGT, ↑ 5’ NT: hepatobiliary disorder

↑ ALP, N GGT, N 5’ NT: bone disorder

MTAP CC2 (7 decks)

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