Alanine aminotransferase
| Alanine aminotransferase | ||
|---|---|---|
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| Ribbon model of the human ALAT2 (monomer, lateral / frontal), pyridoxal phosphate as domes, according to PDB 3IHJ | ||
| Properties of human protein | ||
| Mass / length primary structure | 495 amino acids | |
| Secondary to quaternary structure | Homodimer | |
| Cofactor | Pyridoxal phosphate | |
| Identifier | ||
| Gene names | GPT ; ALAT; OLD | |
| External IDs |
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| Enzyme classification | ||
| EC, category | 2.6.1.2 , transaminase | |
| Response type | Amination | |
| Substrate | L-alanine + α-ketoglutarate | |
| Products | Pyruvate + L-glutamate | |
| Occurrence | ||
| Homology family | Aminotransferase I / II | |
| Parent taxon | Creature | |
The alanine aminotransferase (ALAT, ALT) , formerly glutamate-pyruvate transaminase (GPT) or serum glutamic pyruvic transaminase (SGPT) , is an enzyme that is found mainly in the cytoplasm of liver cells. It needs the coenzyme pyridoxal phosphate (a derivative of vitamin B6) for its function .
It catalyzes the reaction L-alanine + α-ketoglutarate pyruvate + L-glutamate .
This reaction plays an important role in the glucose-alanine cycle , whereby alanine is formed in the muscles from excess nitrogen and pyruvate by ALAT, transported in the blood to the liver and there by ALAT again to pyruvate (for gluconeogenesis ) and nitrogen (for the Urea cycle ).
Laboratory diagnostics
In laboratory diagnostics, the activity of the ALAT is determined from plasma or serum in order to clarify whether there is a liver or biliary tract disease. The reference range for measurements at 37 ° C according to IFCC is up to 50 U / l for men and up to 35 U / l (units per liter) for women. Elevated ALAT values almost always indicate a liver disease in which liver cells have been damaged. For interpretation, the other liver values ( bilirubin , alkaline phosphatase , AST / GOT and GGT ) should also be determined.
Slight increases can be found with fatty liver , liver tumors , liver metastases , liver cell necrosis, cholangitis , gallbladder removal, cholecystectomy, as well as medication or alcohol consumption . Greater increases are found in all chronic hepatitis , cirrhosis of the liver , congestive liver or in toxic liver damage (for example from fungal poisons ). In acute hepatitis, the ALAT can rise to over 5000 U / l. In addition, there is a short-term increase in myocardial infarction .
literature
- Neumeister, Besenthal, Liebrich: Clinical guidelines for laboratory diagnostics , Munich / Jena, Urban & Fischer, 2003, ISBN 3-437-22231-7 .
- Lothar Thomas: Labor und Diagnose , Frankfurt / Main, TH-Books, 2005, ISBN 3-9805215-5-9 .
Web links
- reactome: alanine + alpha-ketoglutarate ⇔ pyruvate + glutamate
- reactome: pyruvate + glutamate ⇔ alanine + alpha-ketoglutarate
- ALT / AST on med4you.at
- Laborlexikon - trade journal for laboratory medicine: GPT ( ISSN 1860-966X )
