Transaminase

In biochemistry, a transaminase or an aminotransferase is an enzyme that catalyzes a type of reaction between an amino acid and an α-keto acid. Specifically, this reaction (transamination) involves removing the amino group from the amino acid, leaving behind an α-keto acid, and transferring it to the reactant α-keto acid and converting it into an amino acid. The enzymes are important in the production of various amino acids, and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases. Transaminases require the coenzyme pyridoxal-phosphate, which is converted into pyridoxamine in the first phase of the reaction, when an amino acid is converted into a keto acid. Enzyme-bound pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha-ketoglutarate, giving alanine, aspartic acid, or glutamic acid, respectively.

The presence of elevated transaminases can be an indicator of liver damage.

Transaminases in amino acid metabolism in animals

Animals must metabolize proteins to amino acids, at the expense of muscle tissue, when blood sugar is low. The preference of liver transaminases for oxaloacetate or alpha-ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to Asp and Glu for conversion to urea for excretion of nitrogen. Similarly, in muscles the use of pyruvate for transamination gives Ala, which is carried by the bloodstream to the liver. Here other transaminases regenerate pyruvate, which provides a valuable precursor for gluconeogenesis. This alanine cycle is analogous to the Cori cycle which allows anaerobic metabolism by muscles.

References

*Ghany, Marc & Hoofnagle, Jay H. (2005). Approach to the Patient With Liver Disease. In Dennis L. Kasper, Anthony S. Fauci, Dan L. Longo, Eugene Braunwald, Stephen L. Hauser, & J. Larry Jameson (Eds.), "Harrison's Principles of Internal Medicine" (16th Edition), pp. 1814–1815. New York: McGraw-Hill.
*Nelson, David L. & Cox, Michael M. (2000). "Lehninger Principles of Biochemistry" (3rd ed.), pp. 628–631, 634, 828–830. New York: Worth Publishers.

ee also

* Valproic acid - a GABA transaminase inhibitor

External links

*


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Look at other dictionaries:

  • transaminase — [ trɑ̃zaminaz ] n. f. • 1964; de trans , amine et ase ♦ Biochim. Enzyme qui transporte le groupement moléculaire NH2 d un corps à un autre. Élévation du taux de transaminases dans le sang lors d une hépatite. ● transaminase nom féminin Enzyme qui …   Encyclopédie Universelle

  • transaminase — |z| s. f. [Bioquímica] Enzima cuja função é transportar os radicais aminados (NH2) de um ácido aminado para outro ácido aminado …   Dicionário da Língua Portuguesa

  • transaminase — [transam′ə nās΄, tranzam′ə nās΄, tranz am′ənāz΄] n. [< TRANSAMINATION + ASE] any of a group of enzymes that cause transamination …   English World dictionary

  • Transaminase — Dieser Artikel oder Abschnitt ist nicht hinreichend mit Belegen (Literatur, Webseiten oder Einzelnachweisen) versehen. Die fraglichen Angaben werden daher möglicherweise demnächst gelöscht. Hilf Wikipedia, indem du die Angaben recherchierst und… …   Deutsch Wikipedia

  • Transaminase — Une transaminase ou aminotransférase est une enzyme qui catalyse un type de réaction entre un acide aminé et un acide α cétonique. Sommaire 1 Biochimie 2 Intérêt médical 2.1 Au niveau hépatique …   Wikipédia en Français

  • transaminase — noun a class of transferases that catalyze transamination (that transfer an amino group from an amino acid to another compound) • Syn: ↑aminotransferase, ↑aminopherase • Hypernyms: ↑transferase • Hyponyms: ↑glutamic oxalacetic transaminase, ↑ …   Useful english dictionary

  • transaminase — aminotransferazė statusas T sritis chemija apibrėžtis Fermentas, katalizuojantis peramininimo reakcijas. atitikmenys: angl. aminotransferase; transaminase rus. аминотрансфераза; трансаминаза ryšiai: sinonimas – transaminazė …   Chemijos terminų aiškinamasis žodynas

  • transaminase — noun Date: 1940 an enzyme promoting transamination called also aminotransferase …   New Collegiate Dictionary

  • transaminase — /trans am euh nays , nayz , tranz /, n. Biochem. any of a class of enzymes, occurring in most plant and animal tissue, that cause transamination. [1940 45; TRANSAMIN(ATION) + ASE] * * * ▪ enzyme also called  Aminotransferase,         any of a… …   Universalium

  • transaminase — noun Any of a group of enzymes that catalyzes transamination. Syn: aminotransferase …   Wiktionary


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