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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 ...
Two-component systems accomplish signal transduction through the phosphorylation of a response regulator (RR) by a histidine kinase (HK). Histidine kinases are typically homodimeric transmembrane proteins containing a histidine phosphotransfer domain and an ATP binding domain, though there are reported examples of histidine kinases in the atypical HWE and HisKA2 families that are not ...
The endothelial protease vasohibin [f] uses a cysteine as the nucleophile, but a serine to coordinate the histidine base. [43] [44] Despite the serine being a poor acid, it is still effective in orienting the histidine in the catalytic triad. [43] Some homologues alternatively have a threonine instead of serine at the acid location. [43]
Histidine, phenylalanine, tryptophan, are essential amino acids for animals. Since they are not synthesized in the human body, they must be derived from the diet. Tyrosine is semi-essential; therefore, it can be synthesized by the animal, but only from phenylalanine.
Histatin's involvement in antimicrobial activities makes histatin part of the innate immune system. [ 2 ] Histatin was first discovered (isolated) in 1988, with functions that's responsible in keeping homeostasis inside the oral cavity, helping in the formation of pellicles, and assist in bonding of metal ions.
Iron is transported by transferrin whose binding site consists of two tyrosines, one aspartic acid and one histidine. [22] The human body has no controlled mechanism for excretion of iron. [23] This can lead to iron overload problems in patients treated with blood transfusions, as, for instance, with β-thalassemia.
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 .