| histidine | <amino acid> An amino acid with an imidazole side chain with a pKa of 6-7. Acts as a proton donor or acceptor and has high potential reactivity and diversity of chemical function. Forms part of the catalytic site of many enzymes. (18 Nov 1997) |
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| histidine ammonia-lyase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |
| histidine deaminase | <enzyme> An enzyme of the lyase class that catalyses the reaction of l-histidine to form urocanate and ammonia. The reaction is the initial step of histidine catabolism. Genetic deficiency of the enzyme, transmitted as an autosomal recessive trait, causes histidinaemia. Chemical name: L-Histidine ammonia-lyase Registry number: EC 4.3.1.3 (12 Dec 1998) |
| histidine decarboxylase | <enzyme> An enzyme that catalyses the decarboxylation of histidine to histamine and carbon dioxide. It requires pyridoxal phosphate in animal tissues, but not in microorganisms. Chemical name: L-Histidine carboxy-lyase Registry number: EC 4.1.1.22 (12 Dec 1998) |
| histidine N-acetyltransferase | <enzyme> Synthesises nalpha-acetyl-l-histidine from l-histidine and acetylcoenzyme a Registry number: EC 2.3.1.33 Synonym: acetyl-CoA - l-histidine n-acetyltransferase, histidine acetyltransferase, coasac - l-histidine n-acetyltransferase, n-acetylhistidine synthetase (26 Jun 1999) |
| histidine permease | <chemical> Hisp, hism and hisq are membrane proteins found in histidine permease (the hisqmp2 complex); also contains the histidine-binding protein hisj Chemical name: permease, histidine Synonym: hisp protein, hism protein, hisq protein, hutm gene product, ee57d gene product (26 Jun 1999) |
| histidine-trna ligase | <enzyme> An enzyme that activates histidine with its specific transfer RNA. Chemical name: L-Histidine:tRNA(His) ligase (AMP-forming) Registry number: EC 6.1.1.21 (12 Dec 1998) |
| protein-histidine kinase | <enzyme> Sass involved in transduction of starvation and cell density inputs; hkna isolated from bacillus thuringiensis; ciah isolated from streptococcus pneumoniae; do not confuse with plp1 protein Registry number: EC 2.7.3.- Synonym: histidine protein kinase, histidine kinase, hkna gene product, ciah gene product, kinc gene product, prrb gene product, plec gene product, mxcq gene product, rese gene product, hpka gene product, comd gene product, plpa gene product (phytochrome-like), divj gene product, sensor histidine kinase, sass gene product (26 Jun 1999) |
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