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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.
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]
Betahistine, sold under the brand name Serc among others, is an anti-vertigo medication.It is commonly prescribed for balance disorders or to alleviate vertigo symptoms.It was first registered in Europe in 1970 for the treatment of Ménière's disease, but current evidence does not support its efficacy in treating it.
It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium. In the liver, urocanic acid is transformed by urocanate hydratase (or urocanase ) to 4-imidazolone-5-propionic acid and subsequently to glutamic acid .
d-Fructose-l-histidine (FruHis) is a ketosamine combining the d-isomer of fructose and the l-isomer of histidine into a functional group. FruHis is present in dried fruits . In interaction with lycopene , FruHis is a potential food related antioxidant and chemopreventive agent, found abundantly in dried tomatoes .
Histidine ammonia-lyase is a cytosolic enzyme catalyzing the first reaction in histidine catabolism, the nonoxidative deamination of L-histidine to trans-urocanic acid. [5] The reaction is catalyzed by 3,5-dihydro-5-methyldiene-4 H -imidazol-4-one (MIO), an electrophilic cofactor which is formed autocatalytically by cyclization of the protein ...
In enzymology, a histidine transaminase (EC 2.6.1.38) is an enzyme that catalyzes the chemical reaction. L-histidine + 2-oxoglutarate (imidazol-5-yl)pyruvate + L-glutamate. Thus, the two substrates of this enzyme are L-histidine and 2-oxoglutarate, whereas its two products are (imidazol-5-yl)pyruvate and L-glutamate.