To Determine Alanine and Aspartate
Transaminase Activity in Serum^25
25.1 Theory
Transaminases are tissue-specific intracellular enzymes, which catalyze reversible
transfer ofα-amino group from amino acid toα-keto acid. They are present in almost
all cells, but higher amounts occur mainly in the liver, brain, heart, and kidney. Two
clinically important transaminases are serum glutamine oxaloacetate transaminase
(SGOT), also called aspartate aminotransferase (AST), and serum glutamine pyru-
vate transaminase (SGPT) also called alanine aminotransferase (ALT). Alanine
transaminase is present in high amount in the cardiac muscles but is also present
significantly in other tissues of the body. ALT shows its high concentration in the
liver and kidney, and trace amounts are present in the skin, pancreas, spleen, lungs,
and cardiac and skeletal muscle. Both AST and ALT enzymes are not excreted in
urine unless a kidney lesion is present. The measurement of these enzymes is a useful
diagnosis indicator of liver functions.
25.2 Specimen Requirements
Serum sample is used which is stable for more than 24 h at 4C. Hemolysis
significantly increases AST levels but moderately increases ALT. Activity in
erythrocytes is almost 6 times higher than the activity in serum. ALT shows higher
day-to-day variation than AST. Its levels are higher in afternoon than morning.
25.3 Principle........................................
The oxaloacetate and pyruvate formed by the action of AST and ALT from appro-
priate substrates couple with dinitrophenyl hydrazine (DNPH) to form a golden
brown or red color in alkaline medium created with NaOH. The intensity of color is
#Springer Nature Singapore Pte Ltd. 2018
V. Kumar, K. D. Gill,Basic Concepts in Clinical Biochemistry: A Practical Guide,
https://doi.org/10.1007/978-981-10-8186-6_25
103