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Histidine (symbol His or H) [2] is an essential amino acid that is used in the biosynthesis of proteins.It contains an α-amino group (which is in the protonated –NH 3 + form under biological conditions), a carboxylic acid group (which is in the deprotonated –COO − form under biological conditions), and an imidazole side chain (which is partially protonated), classifying it as a ...
Carnosine (beta-alanyl-L-histidine) is a dipeptide molecule, made up of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues. [citation needed] Carnosine was discovered by Russian chemist Vladimir Gulevich. [1] Carnosine is naturally produced by the body in the liver [2] from beta-alanine and histidine.
The enzyme histidine decarboxylase (EC 4.1.1.22, HDC) is transcribed on chromosome 15, region q21.1-21.2, and catalyzes the decarboxylation of histidine to form histamine. In mammals, histamine is an important biogenic amine with regulatory roles in neurotransmission , gastric acid secretion and immune response .
α-Fluoromethylhistidine (α-FMH) is an irreversible specific inhibitor of histidine decarboxylase (HDC). [1] It functions by forming a covalent linkage with a catalytic serine residue on the active site of HDC. Due to its efficacy in reducing histamine levels in tissue mast cells, it has many applications in the study of histaminergic systems. [2]
Histamine is derived from the decarboxylation of the amino acid histidine, a reaction catalyzed by the enzyme L-histidine decarboxylase. It is a hydrophilic vasoactive amine. Conversion of histidine to histamine by histidine decarboxylase
Betahistine was once believed to have some positive effects in the treatment of Ménière's disease and vertigo, [3] but more recent evidence casts doubt on its efficacy. [4] [5] Studies of the use of betahistine have shown a reduction in symptoms of vertigo and, to a lesser extent, tinnitus, but conclusive evidence is lacking at present.
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A histamine agonist is a drug which causes increased activity at one or more of the four histamine receptor subtypes.. H 1 agonists promote wakefulness. [1]H 2: Betazole and Impromidine are examples of agonists used in diagnostics to increase histamine.