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Histidine ball and stick model spinning. 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 ...
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.
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.
The same goes for vitamin B12 and ferritin (a form of iron) which women may not get enough of via food, particularly those following plant-based or vegetarian diets.
Histidine initiates the reaction by displacing lysine 305 and forming an aldimine with PLP. Then, histidine's carboxyl group leaves the substrate, forming carbon dioxide . This is the rate-limiting step of the all process, requiring an activation energy of 17.6 kcal/mol [ 12 ] and fitting the experimental turnover of 1.73 s − 1 {\displaystyle ...
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 .
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 ...
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]