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CC 2 LAB > AMINOTRANSFERASES > Flashcards

AMINOTRANSFERASES Flashcards

1
Q

ASPARTATE AMINOTRANSFERASE (AST)

EC

A

E.C. 2.6.1.1

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2
Q

AST

Current name

A

Levo-Aspartate 2-Oxaloglutarate
Aminotransferase

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3
Q

AST

Former name

A

Formerly:
Serum Glutamic Oxaloacetic Transaminase (SGOT)

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4
Q

Physiologic function of AST

A

Involved in the transfer of an amino group between aspartate and a-keto acids.

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5
Q

AST

Coenzyme:

A

Pyridoxal phosphate

Activated - Vitamin B6

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6
Q

Tissue sources of AST

High Concentrations:

A

Cardiac Tissue
Liver
Skeletal Muscle

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7
Q

Tissue Sources of AST

Lower Concentrations:

A

Pancreas
Erythrocytes
Kidney

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8
Q

Diagnostic significance of AST

A

Acute Hepatocellular Disorders

Skeletal Muscle Involvement

Acute Myocardial Infarction (AMI)

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9
Q

Disorder in AST
• Highest levels observed

A

Acute Hepatocellular Disorders

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10
Q

AST in

• In viral hepatitis:

A

up to 100 times Upper Limit Normal

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11
Q

AST in

• In cirrhosis:

A

approximately 4 times Upper Limit Normal

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12
Q

AST

• Levels increase (4-8× ULN)

A

Skeletal Muscle Involvement

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13
Q

MARKER OF ACUTE MYOCARDIAL INFARCTION

AST

Starts
Peaks
Normal

A

Starts - 6-8hrs
Peaks - 18-24hrs
Normal - 4-5days

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14
Q

AST Isoenzymes?
• Cytoplasmic Isoenzyme
• Mitochondrial Isoenzyme

A

• Cytoplasmic Isoenzyme
• Mitochondrial Isoenzyme

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15
Q

AST Isoenzymes

predominant in serum

A

Cytoplasmic Isoenzyme

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16
Q

AST isoenzyme

increased in cellular necrosis

A

Mitochondrial Isoenzyme

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17
Q

AST Isoenzymes

Concentration:
Intracellular AST:

A

7,000 times higher than extracellular

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18
Q

AST Isoenzymes

Clinical Analysis:

A

Isoenzyme analysis not routinely performed

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19
Q

ASSAY FOR ENZYME ACTIVITY
ASPARTATE AMINOTRANSFERASE (AST)

Principle:
Based on ________
Uses a________

A

Karmen Method

coupled enzymatic reaction

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20
Q

ASSAY FOR AST

• Indicator: ______________
• Monitors absorbance change at:_____
• Measures_______ to ______

A

Malate Dehydrogenase

340 nm

NADH oxidation to NAD+

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21
Q

AST

Optimal pH Range:

A

7.3 to 7.8

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22
Q

AST

Reference range:

A

5 to 35 Unit/Liter (37°C) (0.1 to 0.6 ukat/L)

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23
Q

SOURCE OF ERROR
ASPARTATE AMINOTRANSFERASE (AST)

Can dramatically increase serum AST concentration

Should be avoided to ensure accurate results

A

Hemolysis

24
Q

SOURCE OF ERROR
ASPARTATE AMINOTRANSFERASE (AST)

Stability:
• Stable in serum for…

A

3 to 4 days

Optimal at refrigerated temperatures

25
Q

ALANINE AMINOTRANSFERASE (ALT)

EC

A

E.C. 2.6.1.2

26
Q

ALT

Present name

A

Levo-Alanine 2-Oxaloglutarate Aminotransterase

27
Q

ALT

Formerly:

A

Serum Glutamic Pyruvic Transaminase (SGPT)

28
Q

ALT

Physiologic function

A

Catalyzes the transfer of an amino group from alanine to a-ketoglutarate

29
Q

ALT

Produces…

A

glutamate and pyruvate

30
Q

ALT

Coenzyme:

A

Pyridoxal phosphate

(Activated Vitamin B6)

31
Q

ALT is distributed in many tissues, with comparatively high concentrations in the______.

A

liver

32
Q

ALT is more ______ specific than AST

A

Liver

33
Q

ALT Primary Use:

A

Evaluation of hepatic disorders

34
Q

ALT Primary Use:

Higher elevations in_______
Lower elevations in_______

A

hepatocellular disorders

extrahepatic Or intrahepatic obstructive disorders

35
Q

ALT

Acute Liver Inflammation:

ALT elevations often higher than_____

ALT remains elevated longer due______

A

AST

longer half-life (16-24 hours vs. AST)

36
Q

ALT comparison with AST:

A

Helps determine the source of elevated AST

Detects concurrent liver involvement with myocardial injury

37
Q

DIAGNOSTIC SIGNIFICANCE

ALANINE AMINOTRANSFERASE (ALT)

Alcohol-Induced Liver Injury:

Elevated AST/ALT ratio

A

(De Ritis ratio) of 3 to 4:1

38
Q

_______ has a longer halflife

A

Mitochondrial AST

39
Q

Chronic Liver Conditions:

In cirrhosis,_____ often higher than____ as fibrosis progresses

In end-stage cirrhosis, enzyme levels may be____

A

AST; ALT

low

40
Q

AST:ALT ratio

A

Carcinoma, ALD, Cirrhosis of the liver = >2

Hepatitis = <1

41
Q

ASSAY FOR ENZYME ACTIVITY
ALANINE AMINOTRANSFERASE (ALT)

A

Coupled Enzymatic Reaction:

Utilizes Lactate Dehydrogenase (LD) as the indicator enzyme

42
Q

ALT coupled enzymatic reaction

LD catalyzes reduction of____ to _____

Simultaneous oxidation of ____ to ____

A

pyruvate to lactate

NADH to NAD+

43
Q

ALT

Measurement:
• Change in absorbance at______
•______________ to ALT activity

A

340 nm

Directly proportional

44
Q

ALT

Optimal pH:

A

7.3 to 7.8

45
Q

ALT

Reference range:

A

7 to 45 U/L (37°C) (0.1 to 0.8 pkat/L)

46
Q

ASSAY FOR ENZYME ACTIVITY
ALANINE AMINOTRANSFERASE (ALT)

• Colorimetric/Endpoint

A

• Reitman & Frankel

47
Q

ALANINE AMINOTRANSFERASE (ALT)
• Reitman & Frankel

• Color developer:

A

2,4 Dinitrophenylhydrazine (DNPH)

48
Q

ALANINE AMINOTRANSFERASE (ALT)
• Reitman & Frankel
• Colorimetric/Endpoint

• Color intensifier:

A

0.4N Sodium hydroxide (NaOH)

49
Q

Major Organ Affected

AST

ALT

A

Heart

Liver

50
Q

Hemolysis

AST
ALT

A

Affected
Relatively afftected

51
Q

Reitman & Frankel

Substrate

AST
ALT

A

Aspartate a-ketoglutarate

Alanine a-ketoglutarate

52
Q

End products

ALT
AST

A

Oxaloacetate Glutamate

Pyruvate Glutamate

53
Q

Coenzyme

AST
ALT

A

Pyridoxal phosphate (B6)

54
Q

Color developer

AST
ALT

A

2,4 Dinitrophenylhydrazine (DNPH)

55
Q

Color intensifier

AST
ALT

A

0.4N Sodium hydroxide (NaOH)

CC 2 LAB (35 decks)

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