Deamination(redirected from Cytidine deaminase)
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the elimination of an amino group (NH2) from organic compounds. Deamination is accompanied by the substitution of some other group, such as H, OH, OR, or Hal, for the amino group or by the formation of a double bond. In particular, deamination is brought about by the action of nitrous acid on primary amines. In this reaction, acyclic amines yield alcohols (I) and olefins (II), for example:
The deamination of alicyclic amines is accompanied by ring expansion or contraction. In the presence of strong inorganic acids, aromatic amines and nitrous acid yield diazonium salts. Such reactions as hydrolysis, hydrogenolysis, decomposition of quaternary ammonium salts, and pyrolytic reactions also result in deamination.
Deamination plays an important part in the life processes of animals, plants, and microorganisms. Oxidative deamination, with the formation of ammonia and α-keto acids, is characteristic of d-amino acids. Amines also undergo oxidative deamination. Except for glutamate dehydrogenase, which deaminates L-glutamic acid, oxidases of natural amino acids are not very active in animal tissues. Therefore, most L-amino acids undergo indirect deamination by means of prior transamination, with the formation of glutamic acid, which then undergoes oxidative deamination or other transformations. Other types of deamination are reductive, hydrolytic (deamination of amino derivatives of purines, pyrimidines, and sugars), and intramolecular (histidine deamination), which occur mainly in microorganisms.