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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 triad of cytomegalovirus protease [b] uses histidine as both the acid and base triad members. Removing the acid histidine results in only a 10-fold activity loss (compared to >10,000-fold when aspartate is removed from chymotrypsin). This triad has been interpreted as a possible way of generating a less active enzyme to control cleavage ...
The mechanism for the reactions catalyzed by histidine kinase have not been completely elucidated, but current evidence suggests that the catalytic domain of one dimeric unit may rotate in such a way that the ATP binding pocket of that unit can come into contact with a particular histidine residue on the opposite unit and a nucleophilic ...
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 ...
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 .
Imidazole is the side chain of histidine and is typically used at a concentration of 150 - 500 mM for elution. Histidine or histamine can also be used. Decrease in pH; When the pH decreases, the histidine residue is protonated and can no longer coordinate the metal tag, allowing the protein to be eluted.
The Histidine operon leader is an RNA element found in the bacterial histidine operon. At least 6 amino acid operons are known to be regulated by attenuation . [ 1 ] In each a leader sequence of 150–200 bp is found upstream of the first gene in the operon.
Peptide histidine isoleucine (PHI) is part of family that plays a vital role in the cell growth rate such as in the intestine as well as in brain. [3] It was derived from glucagon family called the pituitary adenylate cyclase-activating polypeptide (PACAP) and it has an amino acid sequence homology to vasoactive intestinal peptide , secretin ...