Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
The transfer of an amino group from one molecule to another without the intermediate formation of ammonia. Enzymatic reactions of this type play a prominent role in the formation and ultimate breakdown of amino acids by living organisms. Enzymes that catalyze such reactions are widely distributed and are termed transaminases, or amino-transferases. Perhaps the most prominent transamination reactions in higher animals are those in which glutamate is formed from α-ketoglutarate and other amino acids. See Protein metabolism
a reversible transfer of an amino group (—NH2) from amino acids or amines to keto acids:
The enzymatic transamination reaction, which was discovered in 1937 by the Soviet biochemists A. E. Braunshtein and M. G. Kritsman, is an important link in the process of synthesis and deamination of many amino acids in animals, plants, and microorganisms. Most natural amino acids are synthesized in tissues by the transfer of an NH2 group from glutamic acid, the initial product of nitrogen assimilation, to various keto acids. By permitting rapid interconversion of the various amino and keto acids, the transamination reaction plays an important role in the regulation and coordination of the metabolism of amino acids and carbohydrates.
The enzymes for transamination, transaminases, are found in all living cells. There are more than 55 known transaminases, which catalyze the transamination of all the known natural amino acids and a number of biogenic amines. The coenzyme of transaminases is a derivative of vitamin B6, pyridoxal phosphate, which acts to transfer NH2 groups (for a discussion of the mechanism of transamination, see). A sharp increase in the content of some transaminases in the blood plasma of ill individuals is indicative of damage to the liver (hepatitis), the heart (myocardial infarction), or the muscles (trauma and myodystrophic diseases).
REFERENCESBraunshtein, A. E., and M. M. Shemiakin. “Teoriia protsessov aminokislotnogo obmena, kataliziruemykh piridoksalevymi enzimami.” Biokhimiia, 1953, vol. 18, no. 4.
Meister, A. Biokhimiia aminokislot. Moscow, 1961. (Translated from English.)
The Enzymes, vol. 9. New York, 1973.
IU. M. TORCHINSKII