3. Inhibited by EDTA fluoride Inhibited by oxalate and—
of bone, liver cells, intestine,
Transamination is a process in which an amino group
is transferred from an amino acid to an alpha-ketoacid.
It is an important step in the metabolism of amino
acids. The enzymes responsible for transamination are
called transaminase (now called, amino-transferases).
Two diagnostically useful transaminases are glutamate
oxaloacetate transaminase or GOT or aspartate,
aminotransferase and glutamate pyruvate transaminase or
GPT alanine amino transferase. These enzymes catalyse the
GOT/AST L-aspartate + Oxoglutarate Oxaloacetate+
GPT/ALT L-alanine + Oxoglutarate Pyruvate +
Increased serum transaminase activity is seen in liver
dysfunction. Greater activity of GOT (AST) over GPT (ALT)
is typical of myocardial infarction.
The two methods applied in the analysis of transaminase
activity are colorimetry and ultraviolet spectrophotometry.
The latter procedure requires NADH, coenzyme. The
colorimetric method is discussed below.
The serum specimen submitted for the enzyme assay of
SGOT and SGPT should be free from hemolysis. Collect
the serum by the usual procedure described earlier.
Prompt analysis is recommended and if this is not possible,
Serum Glutamic oxaloacetic transaminase (SGOT)
(AST) (Reitman and Frankel’s Method)
(Courtesy: Tulip Group of Companies)
For the determination of SGOT (AST) activity in serum
(For in vitro diagnostic use only).
SGOT is an enzyme found mainly in heart muscle, liver cells,
skeletal muscle and kidneys. Injury to these tissues results
in the release of the enzyme in bloodstream. Elevated levels
are found in myocardial infarction, cardiac operations,
hepatitis, cirrhosis, acute pancreatitis, acute renal diseases,
primary muscle diseases. Decreased levels may be found in
pregnancy, beri beri and diabetic ketoacidosis.
SGOT converts L-aspartate and α-ketoglutarate to
oxaloacetate and glutamate. The oxaloacetate formed reacts
with 2, 4, Dinitrophenyl hydrazine to produce a hydrazone
derivative, which in an alkaline medium produces a brown
colored complex whose intensity is measured. The reaction
does not obey Beer’s law and hence, a calibration curve
is plotted using a pyruvate standard. The activity of SGOT
(ASAT) is read off this calibration curve.
αKetoglutarate pH 7.4 L-Glutamate
Oxaloacetate Alkaline 2,4,Dinitrophenyl
2,4,DNPH Medium (Brown colored complex)
It is recommended that each laboratory establish its
own normal range representing its patient population.
S : Pyruvate standard (2 mM) 5 mL
Contents are stable at 2–8°C till the expiry mentioned on
the labels. Sodium hydroxide can be stored at RT till the
All reagents are ready to use except NaOH reagent (4N)
which has to be diluted 1:10 with distilled/deionized water.
Working NaOH reagent: Dilute the sodium hydroxide to
250 mL or for every 1.0 mL of NaOH reagent (4N) add 9.0 mL
of distilled water. The working sodium hydroxide reagent is
stable at RT till the expiry mentioned, in a plastic bottle.
Serum. Free from hemolysis SGOT (ASAT) is reported to
be stable in serum for 3 days at 2–8°C.
Wavelength/filter : 505 nm (Hg 546 nm)/green
Plotting of the calibration curve.
Pipette into five clean dry test tubes labeled as 1, 2, 3, 4,
Substrate reagent (L1) 0.50 0.45 0.40 0.35 0.30
Pyruvate standard (S) - 0.05 0.10 0.15 0.20
Distilled water 0.10 0.10 0.10 0.10 0.10
DNPH reagent (L2) 0.50 0.50 0.50 0.50 0.50
Mix well and allow to stand at RT for 20 minutes
Mix well and allow to stand at RT for 10 minutes.
Measure the absorbances of the tubes 2–5 against tube 1
(blank). Plot a graph of the absorbances of tubes 2–5 on
the ‘Y’ axis versus the corresponding enzyme activity on
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