Ch. 13 - Enzymes (GGT - G6PD) (RVSP) Flashcards

0
Q

Serves as the gamma-glutamyl donor in most biologic systems

A

Glutathione

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1
Q

Enzyme involved in the transfer of gamma-glutamyl residue from gamma-glutamyl peptides to amino acids, H2O, and other small peptides

A

Gamma-glutamyltransferase (GGT)

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2
Q

3 functions of GGT

A
  • synthesis of peptides and proteins
  • regulation of tissue glutathione levels
  • transport of amino acids across cell membranes
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3
Q

Tissue sources of GGT

A
Kidney
Brain
Prostate
Pancreas
Liver
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4
Q

Enzyme used for evaluation of liver and biliary system disorders

A

GGT

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5
Q

Enzyme elevated in all hepatobiliary disorders

A

GGT

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6
Q

Enzyme increased in patients receiving enzyme-inducing drugs

A

GGT

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7
Q

Elevated enzyme in chronic alcoholism

A

GGT

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8
Q

Substrate for GGT analysis

A

Gamma-glutamyl-p-nitroanilide

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9
Q

Absorbance range in GGT analysis

A

405-420 nm

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10
Q

Length of time and temperature that GGT activity is stable

A

1 week at 4°C

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11
Q

Reference ranges for GGT

A

M: 6-55 U/L (37°C) (0.1 - 0.9 ukat/L)
F: 5-38 U/L (37°C) (0.1 - 0.6 ukat/L)

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12
Q

Class of amylase

A

Hydrolase

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13
Q

Enzyme that catalyzes the breakdown of starch and glycogen

A

Amylase (AMY)

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14
Q

Enzyme that attacks only alpha, 1-4 glycosidic bonds

A

Alpha-AMY

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15
Q

Degradation products produced after alpha-AMY attacks the alpha, 1-4 glycosidic bonds

A
  • glucose
  • maltose
  • dextrins
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16
Q

Intermediate chains consisting of alpha, 1-6 branching linkages

A

Dextrins

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17
Q

2 components of starch

A

Amylose

Amylopectin

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18
Q

Component of starch; long, unbranched chain of glucose molcules, linked by alpha, 1-4 glycosidic bonds

A

Amylose

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19
Q

Component of starch; branched-chain polysaccharide with alpha, 1-6 glycosidic linkages at the branch points

A

Amylopectin

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20
Q

Important enzyme in the physiologic digestion of starches

A

AMY

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21
Q

2 ions needed by AMY for its activation

A
Calcium ion (Ca2+)
Chloride ion (Cl-)
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22
Q

2 major tissue sources of AMY

A

Acinar cells of the pancreas

Salivary glands

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23
Q

Minor tissue sources of AMY

A

Skeletal muscle
Small intestine
Fallopian tubes
Urine

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24
Q

Smallest enzyme

A

AMY

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25
Q

Where digestion of starches start

A

Mouth

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26
Q

Enzyme in the mouth that hydrolyzes starches

A

Salivary AMY

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27
Q

Performs the major digestive action of starches once the polysaccharides reach the intestine

A

Pancreatic AMY

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28
Q

Inactivates salivary AMY

A

Acidity of gastric contents

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29
Q

Diagnostic significance of serum and urine AMY

A
Acute pancreatitis
Salivary gland lesions
Intraabdominal diseases
Renal insufficiency
Diabetic ketoacidosis
Hyperamylasemia
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30
Q

Time when AMY levels begin to rise in acute pancreatitis

A

5-8 hours after onset of attack

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31
Q

Time when AMY levels are at peak in acute pancreatitis

A

24 hours

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32
Q

Time when AMY levels return to normal in acute pancreatitis

A

3-5 days

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33
Q

Condition when the AMY molecule combines with immunoglobulins to form a complex that is too large to be filtered by the glomerulus

A

Macroamylasemia

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34
Q

AMY isoenzyme derived from pancreatic tissue

A

P-type

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35
Q

AMY isoenzyme derived from salivary gland tissue, fallopian tube and lung

A

S-type

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36
Q

AMY isoenzymes that migrate the fastest in electrophoresis

A

S-type (S1, S2 and S3)

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37
Q

AMY isoenzymes that migrate slowly in electrophoresis

A

P-type (P1, P2 and P3)

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38
Q

Most commonly observed AMY isoenzyme fraction in electrophoresis

A

P2
S1
S2

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39
Q

Predominant AMY isoenzyme in acute pancreatitis and renal failure

A

P3

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40
Q

4 methods for AMY assay

A
  • Amyloclastic/Iodometric method
  • Saccharogenic method
  • Chromolytic/Chromogenic Labelled Substrate method/Colorimetric
  • Couple Enzyme Reaction/Continuous-monitoring technique
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41
Q

AMY method; measures the disappearance of starch substrate

A

Amyloclastic

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42
Q

AMY method; measures the appearance of the product (reducing sugars)

A

Saccharogenic

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43
Q

AMY method; measures the increasing color from production of product coupled with a chromogenic dye

A

Chromogenic/Chromolytic/Colorimetric

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44
Q

AMY method; coupling of several enzyme systems to monitor amylase activity

A

Continuous monitoring/Coupled Enzyme reaction

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45
Q

Optimal pH for AMY activity

A

pH 6.9

46
Q

Length of time and temperature where serum and urine AMY is stable

A

1 week at RT

2 months at 4°C

47
Q

Reference ranges for AMY

A

Serum: 28-100 U/L (37°C) (0.5-1.7 ukat/L)
Urine: 1-15 U/h

48
Q

Enzyme that hydrolyzes the ester linkages of fats to produce alcohols and fatty acids

A

Lipase (LPS)

49
Q

Substrate requirement for LPS in order for activity to occur

A

Emulsion

50
Q

Accelerates LPS reactions

A

Colipase

Bile salt

51
Q

Major tissue source of LPS

A

Pancreas

52
Q

Minor tissue sources of LPS

A

Stomach

Intestine (small)

53
Q

Diagnostic significance of LPS

A

Acute pancreatitis

54
Q

Time when serum LPS activity rises after an attack of acute pancreatitis

A

4-8 hours

55
Q

Time when LPS levels peak in acute pancreatitis

A

24 hours

56
Q

Time when LPS levels decrease in acute pancreatitis

A

8-14 days

57
Q

Enzyme that is more specific for pancreatic disorders than AMY measurement

A

LPS

58
Q

LPS isoenzyme that is the most clinically specific and sensitive

A

L2

59
Q

Classic method for LPS; used an olive oil substrate

A

Cherry-Crandall method

60
Q

LPS method; measures the liberated fatty acids by titration after a 24-hour incubation period

A

Cherry-Crandall method

61
Q

Substrate in Cherry-Crandall method for LPS

A

Olive oil

62
Q

Substrate now used in Cherry-Crandall method for LPS; more pure form of triglyceride

A

Triolein

63
Q

LPS method; measures the rate of clearing n a solution for LPS activity

A

Turbidimetric methods

64
Q

Method for LPS; based on coupled reaction with enzymes such as peroxidase or glycerol kinase

A

Colorimetric methods

65
Q

Lenth of time and temperature when LPS acitivity is stable

A

1 week at RT

3 weeks at 4°C

66
Q

Reference range for LPS

A

<0.6 ukat/L)

67
Q

Enzyme class of G-6-PD

A

Oxidoreductase

68
Q

Tissue sources for G-6-PD

A
Adrenal cortex
Spleen
Thymus
Erythrocytes
Lymph nodes
Lactating mammary gland
69
Q

Inheritance pattern of G-6-PD deficiency

A

Inherited sex-linked trait

70
Q

Maintains NADPH in reduced form

A

G-6-PD

71
Q

Required to regenerate sulfhydryl-containing proteins (ex. glutathione) In its reduced state

A

NADPH

72
Q

Protects Hb from oxidizing agents

A

Glutathione (reduced form)

73
Q

Drug that causes Drug-induced Hemolytic Anemia (DIHA) during G-6-PD deficiency

A

Antimalarial drugs (Primaquine)

74
Q

Hemolytic anemia caused by antimalarial drugs (Primaquine) in the presence of G-6-PD deficiency

A

Drug-Induced Hemolytic Anemia (DIHA)

75
Q

Conditions of increased levels of G-6-PD

A
  • MI

- Megaloblastic anemia

76
Q

Enzyme that does is not elevated during hepatic disorders

A

G-6-PD

77
Q

Specimen used for suspected G-6-PD enzyme deficiency

A

Red cell hemolysate

78
Q

Specimen used for suspected G-6-PD enzyme elevation

A

Serum

79
Q

Reference range for G-6-PD

A

7.9 - 16.3 U/g Hb (0.1 - 0.3 ukat/g Hb)

80
Q

Diagnostic significance of GGT

A
  • Hepatobiliary disorders
  • Enzyme inducing drugs
  • Alcoholism (chronic)
  • Acute pancreatitis
  • Diabetes mellitus
  • MI
  • Differentiating source of ALP elevation
81
Q

Enzyme-inducing drugs

A

Warfarin
Phenobarbital
Phenytoin

82
Q

Method of GGT measurement

A

Sasz Method

83
Q

2 substrates used in Sasz method for GGT

A
  • L-λ-glutamyl-p-nitroanilide (yellow; 405 nm)

- 5-amino-2-nitrobenzoate (410 nm)

84
Q

Salivary gland lesions related to AMY elevation

A

Mumps

Parotitis

85
Q

Intraabdominal disease related to AMY elevations

A
Perforated peptic ulcer
Intestinal obstruction
Cholecystitis
Ruptured ectopic pregnancy
Acute appendicitis
Mesenteric infarction
86
Q

Tissue sources of S-type AMY

A

Salivary gland tissues
Fallopian tubes
Lungs

87
Q

Where does P-type AMY predominate?

A

Urine

88
Q

Where does S-type AMY predominate?

A

Serum

89
Q

AMY mtd; measures the disappearance in initial dark blue color of starch-iodine complex

A

Amyloclastic/Iodometric mtd

90
Q

Reference mtd for AMY

A

Saccharogenic Mtd

91
Q

Number of mg glucose in 30 mins at 37°C at specific assay conditions

A

Somogyi units

92
Q

Wavelength for coupled enzyme reaction for AMY

A

340 nm

93
Q

Substrate for coupled enzyme reaction of AMY

A

Maltotetrase/maltopentoase

94
Q

Inhibits S-type AMY

A

Wheat germ lectin

95
Q

Causes falsely normal levels AMY

A

Plasma triglycerides

96
Q

Inhibits serum AMS activity leading to falsely normal levels in acute pancreatitis with hyperlipemia

A

Plasma triglycerides

97
Q

Causes falsely increased levels of AMY

A

Morphine

Opiates

98
Q

Causes falsely decreased of AMY levels

A

Oxalates

Citrates

99
Q

Conversion factor from Somogyi units to IU

A

1.85

100
Q

Enzyme class of lipase

A

Hydrolase

101
Q

How many days does LPS elevations persist?

A

5 days

102
Q

pH for LPS activity

A

pH 8.6 - 9.0

103
Q

Intraabdominal condition related to LPS elevations

A

Penetrating duodenal ulcers
Intestinal obstruction
Perforated peptic ulcers
Acute cholecystitis

104
Q

Activators for LPS methods

A

Albumin/ionized calcium

105
Q

Inhibitors for LPS methods

A

Heavy metals (ex: quinine)

106
Q

5 methods for LPS activity

A
Turbidimetric Enzyme Reaction
Cherry-Crandall Method (Titrimetric)
Tietz-Borden Mtd
Sigma Tietx
Colorimetric Mtd
107
Q

Substrates for Turbidimetric Enzyme reaction for LPS

A

Olive oil

Triolein

108
Q

Mtd for LPS; decrease in turbidity is measured as LPS hydrolyzes the turbid substrate fat emulsion

A

Turbidimetric Enzyme Reaction

109
Q

Mtd for LPS; measures liberated fatty acids released by alkaline titration after 24 hrs incubation

A

Cherry-Crandall Mtd (Titrimetric)

110
Q

Indicator in Cherry-Crandall Mtd for LPS

A

Phenolphthalein (salmon color)

111
Q

Indicator used in Sigma Tietx

A

Thymolphthalein (blue color)

112
Q

Enzymes used in the Colorimetric mtd for LPS

A

Peroxidase

Glycerol kinase

113
Q

Causes false decrease in LPS levels

A

Hemolysis