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In enzymology, a histidine-tRNA ligase (EC 6.1.1.21) is an enzyme that catalyzes the chemical reaction. ATP + L-histidine + tRNAHis AMP + diphosphate + L-histidyl-tRNAHis. The 3 substrates of this enzyme are ATP, L-histidine, and tRNA(His), whereas its 3 products are AMP, diphosphate, and L-histidyl-tRNA(His).
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 Pauly reaction is a chemical test used for detecting the presence of tyrosine or histidine in proteins. It is named after German chemist Hermann Pauly , who first described the reaction. [ 1 ] When proteins containing either tyrosine or histidine are reacted with diazotized sulfanilic acid under alkaline conditions, a red color is formed by ...
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 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]
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.
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 ...
In enzymology, a histidine N-acetyltransferase (EC 2.3.1.33) is an enzyme that catalyzes the chemical reaction. acetyl-CoA + L-histidine CoA + N-acetyl-L-histidine. Thus, the two substrates of this enzyme are acetyl-CoA and L-histidine, whereas its two products are CoA and N-acetyl-L-histidine.