Amination

The amination is a nucleophilic substitution, in which a heteroatom ( such as oxygen or halogen ) is bonded to a carbon atom is replaced with an amino compound. In the simplest case, it is ammonia, but it may also be a primary, secondary or tertiary amine.

A distinction between reductive amination catalytic amination and transamination. A known name reaction is the technically important Leuckart - Wallach reaction, reductive amination.

Biological Significance

In the metabolism is effected by reductive amination of the conversion of ammonia and α -keto acids ( ketocarboxylic acids ) to the corresponding α -amino acids. For example, α -ketoglutaric acid is converted to glutamic acid in the presence of ammonia in the mitochondria. The toxic effect of ammonia was partly due to this reaction, since this α -ketoglutaric acid is withdrawn from the citric acid cycle and thus mitochondrial respiration coupled to the citric acid cycle, comes to a halt. In addition to the reductive amination in metabolism is the transamination of particular importance:

The degradation of proteins, the peptide bonds by endo - and exopeptidases are cleaved hydrolytically. If the amino acids are further degraded, the organism, the release of ammonia ( NH3) must prevent, as this is a potent cytotoxin. Most amino acids are therefore first transamination. In this process, for the pyridoxal phosphate ( PLP P5P or PALP ) is required as a co- substrate, the amino group is transferred to an α -keto acid (2- oxo ), wherein an α -keto acid of the amino acid and from the previous α -keto acid is an amino acid.