Alanine aminotransferase (ALT/GPT) Assay Kits

Alanine aminotransferase (ALT) is an enzyme that catalyzes the conversion of alanine and α-ketoglutarate through amino group transfer¹⁾. Previously known as glutamate pyruvate transaminase (GPT), its name was revised to conform to international nomenclature standards. ALT is involved in intracellular amino acid metabolism and gluconeogenesis in the liver²⁾, and two isoforms, ALT1 and ALT2, have been identified. ALT1 is localized in the cytosol, while ALT2 is found in the mitochondria³⁾. Both isoforms are highly abundant in liver tissue³⁾, whereas their expression levels are low in non-hepatic tissues in rats and humans⁴⁾. Given these characteristics, ALT is widely used as a primary marker of liver dysfunction.

Serum ALT activity increases in various liver diseases, including viral infections, liver cirrhosis, and metabolic dysfunction-associated steatohepatitis (MASH). However, ALT levels can also be elevated due to non-hepatic conditions, and some patients with liver disease may not exhibit elevated ALT levels. Therefore, interpretation of ALT activity data requires caution, particularly when non-hepatic factors cannot be ruled out^3,5).

When a sample is mixed with Substrate-Enzyme Solution and α-KG Solution, glutamate and pyruvate are formed from L-alanine and α-ketoglutarate in a reaction catalyzed by ALT in the sample. The pyruvate thus produced is converted to lactate by lactate dehydrogenase (LD). At the same time, NADH is oxidized to NAD, and the absorbance at 340 nm decreases. Finally, the reaction is stopped using a reaction Stop Solution, and the absorbance is measured to determine the ALT activity value in the sample.

LabAssay™ ALT (GPT) is a kit for measuring ALT in blood (serum, plasma). With the use of microplate, this kit provides a quick and convenient method for measuring ALT in samples.

[Note] LabAssay™ series are reagents for research purposes. They cannot be used for diagnostic purposes.

Kit Performance

1. Vroon D.H., and Israili Z.: “Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.”, Boston, chap.99(1990).
2. DeRosa, G., and Swick, R. W.: J. Biol. Chem., 250(20), 7961(1975).
   Metabolic implications of the distribution of the alanine aminotransferase isoenzymes
3. Yang, R. Z., et al.: Hepatology (Baltimore, Md.), 49(2), 598(2009).
   Alanine aminotransferase isoenzymes: molecular cloning and quantitative analysis of tissue expression in rats and serum elevation in liver toxicity
4. Boyd J. W.: Vet. Clin. Pathol., 12(2), 9(1983).
   The mechanisms relating to increases in plasma enzymes and isoenzymes in diseases of animals
5. Ruhl C. E., and Everhart J. E.: Gastroenterology, 124(7), 1821(2003).
   Relation of elevated serum alanine aminotransferase activity with iron and antioxidant levels in the United States