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CC 2 LEC > Miscallaneous Enzymes > Flashcards

Miscallaneous Enzymes Flashcards

1
Q

GAMMA-GLUTAMYL
TRANSFERASE (GGT)

EC

A

E.C. 2.3.2.2

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2
Q

GGT other name

A

(5-Glutamyl) Peptide: Amino Acid-5-Glutamyl-Transferase

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3
Q

Involved in the transfer of the gamma-glutamyl residue from gamma-glutamyl peptides to amino acids, H20, and other small peptides

A

GAMMA-GLUTAMYL
TRANSFERASE (GGT)

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4
Q

PHYSIOLOGY
Has not been clearly established
Involved in peptide and protein synthesis
Regulation of tissue glutathione levels
Transport of amino acids across cell membranes

A

GAMMA-GLUTAMYL
TRANSFERASE (GGT)

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5
Q

TRANSFERASE (GGT)
TISSUE SOURCES

A
  • Kidney
  • Brain
  • Prostate
  • Pancreas
  • Liver (canaliculi of the hepatic cells)
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6
Q

GAMMA-GLUTAMYL TRANSFERASE (GGT)
DIAGNOSTIC SIGNIFICANCE
• Elevated in all_______ disorders
- Biliary tract obstruction
• Increased in patients receiving enzyme-inducing drugs
-(3)

A

hepatobiliary

warfarin, phenobarbital, phenytoin

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7
Q

GAMMA-GLUTAMYL TRANSFERASE (GGT)

• Increased in chronic….
• Useful in monitoring abstention from alcohol
• Normalizes_____ weeks after cessation of drinking

A

alcoholism/excessive alcohol consumption

2-3

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8
Q

GAMMA-GLUTAMYL TRANSFERASE (GGT)

ASSAY

TEST PRINCIPLE
GGT catalyzes the transfer of a Gamma-Glutamyl group from Gamma-Glutamyl-p-Nitroanilide (GPNA) to Glycylglycine to form Gamma-Glutamyl-Glycylglycine and p-Nitroaniline.

A

SZASZ ASSAY

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9
Q

GLUCOSE-6-PHOSPHATE DEHYDROGENASE (G6PD\tin

EC

A

• E.C. 1.1.1.49

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10
Q

• D-Glucose-6-Phosphate: NADP+ 1-
Oxidoreductase

A

GLUCOSE-6-PHOSPHATE DEHYDROGENASE (G6PD)

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11
Q

Catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconate or 6-phosphogluconolactone

A

G6PD

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12
Q

Reaction is important in the pentose-phosphate shunt of glucose metabolism with the ultimate production of NADPH

A

G6PD

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13
Q

DIAGNOSTIC SIGNIFICANCE
• RBC

  • Maintain NADPH in reduced form
  • Required to regenerate glutathione from the oxidized to the reduced state
    • Reduced glutathione protects Hgb from oxidation
A

GLUCOSE-6-PHOSPHATE
DEHYDROGENASE (G6PD)

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14
Q

•Low_____ = low NADPH = low reduced glutathione= hemolysis

A

G6PD

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15
Q

A red cell hemolysate is used to assay for deficiency of the enzyme;

serum is used for evaluation of enzyme elevations

A

G6PD

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16
Q

ANGIOTENSIN-CONVERTING ENZYME (ACE)

EC

A

• E.C. 3.4.15.1

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17
Q

• Other names: Kininase Il and Peptidyl-Dipeptidase A

A

ACE

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18
Q

• Hydrolysis of peptide bonds at a free C-terminus releasing a dipeptide in the reaction

A

ACE

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19
Q

• Cleaves His-Leu sequence in Angiotensin 1 to form Angiotensin 2
• Contains Zinc in its active site

20
Q

• Tissue-bound, with much lower levels circulating in plasma
• Predominantly found in endothelial cell membranes throughout the body

A

ANGIOTENSIN-CONVERTING ENZYME (ACE)

21
Q
  • rich in ACE
A

• Lungs and Testes

22
Q

ANGIOTENSIN-CONVERTING ENZYME (ACE)
Measurement
• Measured by its ability to cleave synthetic peptides, releasing…

A

hippuric acid

23
Q

ANGIOTENSIN-CONVERTING ENZYME (ACE)
Causes of Abnormal Results

  • Abnormal collection of inflammatory cells called granulomas may appear on the body (overreaction of the immune system
  • Any part of the body can be affected but the most commonly affected areas are the lungs, skin, eyes and lymph nodes
A

SARCOIDOSIS

24
Q

5’-nucleotidase (5’n)
EC

A

• E.C. 3.1.3.5

25
Q

• 5’-Ribonucleotide Phosphohydrolase

A

5’-nucleotidase (5’n)

26
Q

• Is a cytoplasmic membrane-bound phosphatase
• Acts only on nucleotides

A

5’-nucleotidase (5’n)

27
Q

• Functions in extracellular adenosine production, nutrient absorption, and cell proliferation

5’-Ribonucleotide + HO -> Ribonucleoside + Phosphate

A

5’-nucleotidase (5’n)

28
Q

• A metalloenzyme (zinc)
• Widely distributed in the body, predominantly attached to cell membranes (like ALP and GGT)

A

5’-nucleotidase (5’n)

29
Q

• Plasma levels are predominantly derived from the liver
• Commonly used to determine if the source of an elevated ALP is from liver or bone

A

5’-nucleotidase (5’n)

30
Q

Measurement
• Difficult because other phosphatases like ALP can cleave the substrate
- Remedy: to use ALP inhibitors like theophylline and levamisole

A

5’-nucleotidase (5’n)

31
Q

• Chelating agents inhibit activity (EDTA inhibits enzyme activity)

A

5’-nucleotidase (5’n)

32
Q

CHOLINESTERASE (ChE)

• Acetylcholinesterase or ‘true’ cholinesterase (choline esterase 1) or RBC cholinesterase

A

• E.C. 3.1.1.7

33
Q

• Pseudocholinesterase (choline esterase 2) or plasma cholinesterase

A

• E.C. 3.1.1.8

34
Q

: found in the nervous system, neuromuscular junctions, and RBCs

A

CHOLINESTERASE (ChE)

“True” AChE

35
Q

is made from choline and acetyl CoA.

A

Acetylcholine (ACh)

36
Q

In the synaptic cleft ACh is rapidly broken down by the enzyme______.

A

acetylcholinesterase

37
Q

is produced by the liver and hydrolyzes choline esters

A

CHOLINESTERASE (ChE)

• E.C. 3.1.1.8
• Pseudocholinesterase

38
Q

CHOLINESTERASE (ChE)
Measurement

A

• Ellman’s Method

39
Q

Che

  • Substrate:
  • Released thiocholine react with…
  • Product:
A

acylthiocholine ester

Ellman’s reageant

5-mercapto-2-nitro benzoic acid

40
Q

CHOLINESTERASE (ChE)
Measurement
-: Serum
: Hemolysate of washed RBC

A

PseudoChE

True ChE

41
Q

CHOLINESTERASE (ChE)
Why measure?
E-C. 3.1.1.8.
• PseudoChE

-_________
( a Irreversible inhibitors of both AchE and PChE
PChE activity falls before AChE activity
- PChE reflects acute toxicity; AChE reflects chronic exposure

A

Organophosphate Insecticides

42
Q
  • May be inherited or acquired
  • May lead to an increased sensitivity to the muscle relaxants succinylcholine and mivacurium
  • Amplified duration of apnea and paralysis (from 4-6
    minutes normally to 8 hours)
A

PseudoChE deficiency

43
Q

Neural tube defects
Spina Bifida
Anencephaly
Encephalocele

A

CHOLINESTERASE (ChE)

44
Q

Aldolase (ald)

EC

45
Q

D-fructose-1,6-bisdiphosphate
D-glyceraldehyde-3-phosphate-lyase

46
Q

Aldolase (ald)
Isoenzymes:
- Aldolase A

  • Aldolase B
  • Aldolase C
A

• Skeletal muscles

• WBC, liver, kidneys

• Brain tissue

CC 2 LEC (13 decks)

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