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Related to histidine: histidine decarboxylase


(hĭs`tĭdēn), organic compound, one of the 22 α-amino acidsamino acid
, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.
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 commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. Histidine is the direct precursor of histaminehistamine
, organic compound derived in the body from the amino acid histidine by the removal of a carboxyl group (COOH). Although found in many plant and animal tissues, histamine is specifically important in human physiology because it is one of the chemicals released from
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; it is also an important source of carbon atoms in the synthesis of purinespurine,
type of organic base found in the nucleotides and nucleic acids of plant and animal tissue. The German chemist Emil Fischer did much of the basic work on purines and introduced the term into the chemical literature in the early 20th cent.
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. The imidazole group on the side chain of histidine can act as both an acid and a base, i.e., it can both donate and accept protons under some conditions. This turns out to be an important property when histidine is incorporated into proteinsprotein,
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
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, particularly when it becomes a part of the primary structure of some enzymesenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
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. It is thought that the side chain of this amino acid acts as a general acid and base as it participates in the catalytic functions of chymotrypsinchymotrypsin
, proteolytic, or protein-digesting, enzyme active in the mammalian intestinal tract. It catalyzes the hydrolysis of proteins, degrading them into smaller molecules called peptides. Peptides are further split into free amino acids.
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, as well as those of a number of enzymes dealing with the metabolism of carbohydrates, proteins, and nucleic acids. It has even been implicated in the workings of cocoonase, the enzyme that allows adult silk moths to escape from their cocoons. Histidine is considered to be an essential amino acid for infants (it must be supplied in the diet); experiments with adults indicate that they can go for at least short periods without dietary intake of this amino acid. It was isolated from protein in 1896; its structure was confirmed by chemical synthesis in 1911.



(α-amino-β-imidazole-propionic acid):

an amino acid with basic characteristics, essential in many animals; the human body is capable of limited synthesis of histidine. It is one of the ingredients of the active centers of many enzymes, in particular of ribonuclease and transketolase. The initial stage of the enzymatic destruction of histidine in the body is the splitting off of ammonia, with the formation of urocanic acid, which is discharged in the urine. The deamination of histidine is an irreversible reaction and is catalyzed by the enzyme histidine ammonia lyase (histidine-a-deaminase), which is found in the liver of animals and in bacteria. Histidine deficiency leads to many metabolic disturbances, including inhibition of hemoglobin synthesis. Histidine is a precursor of the specific dipeptides of the skeletal musculature—carnosine and anserine. Decarboxylation of histidine leads to the formation of the biologically active amine histamine; this process is catalyzed by histidine decarboxylase, an enzyme belonging to the class of lyases. This enzyme acts only on the L-isomer (natural form) of histidine. The reaction is reversibly inhibited by the respiratory inhibitors cyanide, hydroxylamine, and semicarbazide.



C6H9O2N3 A crystalline basic amino acid present in large amounts in hemoglobin and resulting from the hydrolysis of most proteins.
References in periodicals archive ?
The candidates, serine, threonine, arginine, asparagine, lysine, histidine, tyrosine, glutamine, and cysteine as well as glycine, as a negative control, were analyzed.
For example, when the concentration of citric acid, oxalic acid, and histidine was 6 mmol/L, the desorbability of Cd was 84.
4] M and those of seine, tyrosine, lysine, and histidine were prepared to be 5.
Sjolin, Orientation of Histidine Residues in RNase A: Neutron Diffraction Study, Proc.
com announces Global Sorbitol Industry 2015 Market Research Report of 155 pages and Global Histidine Industry 2015 Market Research Report of 140 pages added to its research database.
In contrast to generally used broad-spectrum proteases, Maxipro HSP is able to mildly and selectively hydrolyze protein in side streams due to its high selectivity for the amino acid histidine.
In this research, nanotubes modified with histidine were used to modify the disadvantages of NafionEeA membrane in fuel cells, including high passing of fuel, low conductivity of proton, and low operational temperature.
Glutamic acid, phenylalanine, histidine and lysine contents were high.
Histamine is a biogenic amine (sometimes referred to as a vasoactive amine) that, in mammals, is produced primarily by the action of the enzyme histidine decarboxylase on the amino acid histidine.
The effects of GanedenBC30 with protein were examined in a randomized, double-blind crossover clinical trial on key amino acids, including leucine (the regulator for muscle protein synthesis), isoleucine and valine (branched chain amino acids), as well as histidine, alanine, asparagines, citrulline, cystine, glutamine (a key amino acid for supporting ph balance and the immune system), methionine, ornthinine, serine, threonine, tryptophan and phenylalanine.
Addition of 200 mg/liter histidine and beta-alanine (separately or in combination) had no effect on the mean life span of flies.