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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 ...
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 .
Aluminium, the third most common element in the Earth's crust (after oxygen and silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body. [38] Transferrins can bind aluminium. [39]
C. albicans with a deletion of CHK1, the two-component histidine kinase gene, show defects in morphogenesis and a drastic decrease in the cell’s ability to resist elimination by human neutrophils. As humans lack this two-component system, it may be a good target for anti-microbial agents in order to treat candidiasis .
A polyhistidine-tag, best known by the trademarked name His-tag, is an amino acid motif in proteins that typically consists of at least six histidine (His) residues, often at the N- or C-terminus of the protein. It is also known as a hexa histidine-tag, 6xHis-tag, or His6 tag.
The table below lists the abundance of amino acids in E.coli cells and the metabolic cost (ATP) for synthesis of the amino acids. Negative numbers indicate the metabolic processes are energy favorable and do not cost net ATP of the cell. [12] The abundance of amino acids includes amino acids in free form and in polymerization form (proteins).
The histidine phosphotransfer function can be carried out by proteins with at least two different architectures, both composed of a four-helix bundle but differing in the way the bundle is assembled. Most structurally characterized HPt proteins, such as the Hpt domain from the Escherichia coli protein ArcB and the Saccharomyces cerevisiae ...
H 1-antihistamines work by binding to histamine H 1 receptors in mast cells, smooth muscle, and endothelium in the body as well as in the tuberomammillary nucleus in the brain. Antihistamines that target the histamine H 1-receptor are used to treat allergic reactions in the nose (e.g., itching, runny nose, and sneezing).