AMINOTRANSFERASES

Question 1

ASPARTATE AMINOTRANSFERASE (AST)

EC

Answer 1

E.C. 2.6.1.1

Question 2

AST

Current name

Answer 2

Levo-Aspartate 2-Oxaloglutarate
Aminotransferase

Question 3

AST

Former name

Answer 3

Formerly:
Serum Glutamic Oxaloacetic Transaminase (SGOT)

Question 4

Physiologic function of AST

Answer 4

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

Question 5

AST

Coenzyme:

Answer 5

Pyridoxal phosphate

Activated - Vitamin B6

Question 6

Tissue sources of AST

High Concentrations:

Answer 6

Cardiac Tissue
Liver
Skeletal Muscle

Question 7

Tissue Sources of AST

Lower Concentrations:

Answer 7

Pancreas
Erythrocytes
Kidney

Question 8

Diagnostic significance of AST

Answer 8

Acute Hepatocellular Disorders

Skeletal Muscle Involvement

Acute Myocardial Infarction (AMI)

Question 9

Disorder in AST
• Highest levels observed

Answer 9

Acute Hepatocellular Disorders

Question 10

AST in

• In viral hepatitis:

Answer 10

up to 100 times Upper Limit Normal

Question 11

AST in

• In cirrhosis:

Answer 11

approximately 4 times Upper Limit Normal

Question 12

AST

• Levels increase (4-8× ULN)

Answer 12

Skeletal Muscle Involvement

Question 13

MARKER OF ACUTE MYOCARDIAL INFARCTION

AST

Starts
Peaks
Normal

Answer 13

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

Question 14

AST Isoenzymes?
• Cytoplasmic Isoenzyme
• Mitochondrial Isoenzyme

Answer 14

• Cytoplasmic Isoenzyme
• Mitochondrial Isoenzyme

Question 15

AST Isoenzymes

predominant in serum

Answer 15

Cytoplasmic Isoenzyme

Question 16

AST isoenzyme

increased in cellular necrosis

Answer 16

Mitochondrial Isoenzyme

Question 17

AST Isoenzymes

Concentration:
Intracellular AST:

Answer 17

7,000 times higher than extracellular

Question 18

AST Isoenzymes

Clinical Analysis:

Answer 18

Isoenzyme analysis not routinely performed

Question 19

ASSAY FOR ENZYME ACTIVITY
ASPARTATE AMINOTRANSFERASE (AST)

Principle:
Based on ________
Uses a________

Answer 19

Karmen Method

coupled enzymatic reaction

Question 20

ASSAY FOR AST

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

Answer 20

Malate Dehydrogenase

340 nm

NADH oxidation to NAD+

Question 21

AST

Optimal pH Range:

Answer 21

7.3 to 7.8

Question 22

AST

Reference range:

Answer 22

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

Question 23

SOURCE OF ERROR
ASPARTATE AMINOTRANSFERASE (AST)

Can dramatically increase serum AST concentration

Should be avoided to ensure accurate results

Answer 23

Hemolysis

Question 24

SOURCE OF ERROR
ASPARTATE AMINOTRANSFERASE (AST)

Stability:
• Stable in serum for…

Answer 24

3 to 4 days

Optimal at refrigerated temperatures

Question 25

ALANINE AMINOTRANSFERASE (ALT) EC

Answer 25

E.C. 2.6.1.2

Question 26

ALT Present name

Answer 26

Levo-Alanine 2-Oxaloglutarate Aminotransterase

Question 27

ALT Formerly:

Answer 27

Serum Glutamic Pyruvic Transaminase (SGPT)

Question 28

ALT Physiologic function

Answer 28

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

Question 29

ALT Produces…

Answer 29

glutamate and pyruvate

Question 30

ALT Coenzyme:

Answer 30

Pyridoxal phosphate (Activated Vitamin B6)

Question 31

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

Answer 31

liver

Question 32

ALT is more ______ specific than AST

Answer 32

Liver

Question 33

ALT Primary Use:

Answer 33

Evaluation of hepatic disorders

Question 34

ALT Primary Use: Higher elevations in_______ Lower elevations in_______

Answer 34

hepatocellular disorders extrahepatic Or intrahepatic obstructive disorders

Question 35

ALT Acute Liver Inflammation: ALT elevations often higher than_____ ALT remains elevated longer due______

Answer 35

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

Question 36

ALT comparison with AST:

Answer 36

Helps determine the source of elevated AST Detects concurrent liver involvement with myocardial injury

Question 37

DIAGNOSTIC SIGNIFICANCE ALANINE AMINOTRANSFERASE (ALT) Alcohol-Induced Liver Injury: Elevated AST/ALT ratio

Answer 37

(De Ritis ratio) of 3 to 4:1

Question 38

_______ has a longer halflife

Answer 38

Mitochondrial AST

Question 39

Chronic Liver Conditions: In cirrhosis,_____ often higher than____ as fibrosis progresses In end-stage cirrhosis, enzyme levels may be____

Answer 39

AST; ALT low

Question 40

AST:ALT ratio

Answer 40

Carcinoma, ALD, Cirrhosis of the liver = >2 Hepatitis = <1

Question 41

ASSAY FOR ENZYME ACTIVITY ALANINE AMINOTRANSFERASE (ALT)

Answer 41

Coupled Enzymatic Reaction: ***Utilizes Lactate Dehydrogenase (LD)*** as the indicator enzyme

Question 42

ALT coupled enzymatic reaction LD catalyzes reduction of____ to _____ Simultaneous oxidation of ____ to ____

Answer 42

pyruvate to lactate NADH to NAD+

Question 43

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

Answer 43

340 nm Directly proportional

Question 44

ALT Optimal pH:

Answer 44

7.3 to 7.8

Question 45

ALT Reference range:

Answer 45

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

Question 46

ASSAY FOR ENZYME ACTIVITY ALANINE AMINOTRANSFERASE (ALT) • Colorimetric/Endpoint

Answer 46

• Reitman & Frankel

Question 47

ALANINE AMINOTRANSFERASE (ALT) • Reitman & Frankel • Color developer:

Answer 47

2,4 Dinitrophenylhydrazine (DNPH)

Question 48

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

Answer 48

0.4N Sodium hydroxide (NaOH)

Question 49

Major Organ Affected AST ALT

Answer 49

Heart Liver

Question 50

Hemolysis AST ALT

Answer 50

Affected Relatively afftected

Question 51

Reitman & Frankel Substrate AST ALT

Answer 51

Aspartate a-ketoglutarate Alanine a-ketoglutarate

Question 52

End products ALT AST

Answer 52

Oxaloacetate Glutamate Pyruvate Glutamate

Question 53

Coenzyme AST ALT

Answer 53

Pyridoxal phosphate (B6)

Question 54

Color developer AST ALT

Answer 54

2,4 Dinitrophenylhydrazine (DNPH)

Question 55

Color intensifier AST ALT

Answer 55

0.4N Sodium hydroxide (NaOH)