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## Metabolism of amino acids: Decarboxylations

Principle

Specific enzymes for each amino acid called decarboxylases catalyze the release of $CO_2$:

## Special cases of decarboxylation

Lysine

The cadaverine produced can be revealed by colored indicators. The reaction is the basis of a medical test to detect bacteria causing cystitis, typhus, pneumonia or cholera.

5-Hydroxytryptophan

The serotonin produced is a neurotransmitter. It is transformed in the pineal gland into melatonin that regulates sleep:

Tryptophan

The tryptamine produced plays a role in nerve transmission by modulating the effect of serotonin.

Histidine

The histamine produced plays a central role in the immune response. It makes the walls of capillary vessels permeable to white blood cells and pathogens.

Serine

The ethanolamine (2-aminoethane) produced occurs in the composition of most phospholipids that make up the cell walls.

Tyrosine

The tyramine produced is widely present in animal or vegetable food. ($\tau \upsilon \rho$ = cheese!).