Histidindekarboxylas

Histidindekarboxylas, also known as histidine decarboxylase (HDC), is an enzyme that catalyzes the conversion of the amino acid histidine into histamine. This reaction is a crucial step in the biosynthesis of histamine in many organisms. Histamine is a biogenic amine with diverse physiological roles, acting as a neurotransmitter, a mediator of immune responses, and a regulator of gastric acid secretion.

The enzyme HDC is found in various tissues and cell types, including mast cells, basophils, neurons, and enterochromaffin-like cells in the stomach. Its activity is essential for the proper functioning of these systems. For instance, in the immune system, histamine released by HDC activity contributes to allergic reactions and inflammation. In the brain, it plays a role in regulating sleep-wake cycles, appetite, and cognitive functions.

The gene encoding histidine decarboxylase is highly conserved across species. The enzyme typically requires pyridoxal phosphate (PLP), a derivative of vitamin B6, as a cofactor for its catalytic activity. The decarboxylation of histidine by HDC produces histamine and carbon dioxide. This process is tightly regulated to ensure appropriate levels of histamine are maintained within the body. Dysregulation of HDC activity has been implicated in various pathological conditions, including allergies, inflammatory diseases, and certain neurological disorders.