Transamination

There are two chemical reactions known as transamination (or aminotransfer). The first is the reaction between an amino acid and an alpha-keto acid. The amino group is transferred from the former to the latter; this results in the amino acid being converted to the corresponding α-keto acid, while the reactant α-keto acid is converted to the corresponding amino acid (if the amino group is removed from an amino acid, an α-keto acid is left behind).

Transamination in biochemistry is accomplished by enzymes called transaminases or aminotransferases. The human body synthesizes the 10 non-essential amino acids and transamination is the process by which most of these syntheses occur. The chirality of an amino acid is determined during transamination.This reaction uses the coenzyme PLP, and is considered to be a kinetically perfect reaction. The product of transamination reactions depend on the availability of alpha-keto acids. The products usually are either alanine, aspartate or glutamate, since their corresponding alpha-keto acids are produced through metabolism of fuels.

The second type of transamination reaction, which can be described as an alkylamino-de-amination is a nucleophilic substitution of one amine or amide anion on an amine or ammonium salt. [Smith, M. B. and March, J. "Advanced Organic Chemistry: Reactions, Mechanisms, and Structure", 5th ed. Wiley, 2001, p. 503. ISBN 0471585890] For example, the attack of a primary amine by a primary amide anion can be used to prepare secondary amines:

:RNH₂ + R'NH⁻ → RR'NH + NH₂⁻

Symmetric secondary amines can be prepared using Raney nickel (2RNH₂ → R₂NH + NH₃). And finally, quaternary ammonium salts can be dealkylated using ethanolamine:

:R₄N⁺ + NH₂CH₂CH₂OH → R₃N + RN⁺H₂CH₂CH₂OH

ee also

* Transaminase

References

External links

* [http://www.rpi.edu/dept/bcbp/molbiochem/BiochSci/sbello/new_page_2.htm Overview of amino acid synthesis]
* [http://www2.ufp.pt/~pedros/bq/urea.htm The chemical logic behind aminoacid degradation and the urea cycle]