Deamination

As deamination is called the chemical cleavage of an amino group as ammonium ion or ammonia. Deaminations take place both in biochemistry and in chemical engineering processes. A distinction is oxidative, hydrolytic and eliminative deamination.

Deamination is the first step of the biochemical degradation of amino acids. In mammals, this process is mainly from the liver. The ammonium formed is then converted into urea in order to prevent cytotoxic effects of the conjugate base is ammonia.

Oxidative ( dehydrating ) deamination

In the first step of the oxidative deamination of the amino group of the amino acid L-glutamate is oxidized by hydrogen abstraction of the imino group, wherein the hydrogen to NAD or NADP is transmitted. This is followed by hydrolytic cleavage of the imino group and the formation of an ammonium ion, and α -keto acid, the α -ketoglutarate.

Also FMN and FAD to catalyze redox reactions, including oxidative deamination. They are in contrast to the soluble NAD or NADP bound as prosthethische group to their enzyme and must there also be regenerated.

Hydrolytic deamination

Here, ammonia ( NH3) is split off by hydrolysis of the amide group of an amino acid. The amide group is cleaved by water retention and replaced by an OH group. Accordingly, acid amides from carboxylic acids are formed ( COOH group ).

Further utilization of the ammonia released

The liberated during the deamination of amino acids, ammonia represents a cell poison and must be bound or excreted accordingly. It may on the one hand be bound to alpha-keto acids, which are thus amino acids or it is excreted in the urine. The latter is done in the human body primarily by the synthesis of urea in the urea cycle, which takes place in the liver. Subsequently, the urea is supplied to the blood and excreted via the kidneys in the urine. Moreover, the kidney has a mechanism that leads to the direct excretion of ammonia via the urine. The simultaneous transport of ammonia (NH3) and protons (H ) in the renal tubules leads to connect this to an ammonium ion ( NH4 ). Ammonium can not pass through the membrane of the kidney cells and is excreted in the urine. ( However, this is primarily the regulation of acid-base balance, because as protons are removed from the body, which is important in compensating for acidosis. )