1kmm
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HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE
OverviewOverview
The crystal structure of an enzyme-substrate complex with histidyl-tRNA, synthetase from Escherichia coli, ATP, and the amino acid analog, histidinol is described and compared with the previously obtained, enzyme-product complex with histidyl-adenylate. An active site arginine, Arg-259, unique to all histidyl-tRNA synthetases, plays the role of the, catalytic magnesium ion seen in seryl-tRNA synthetase. When Arg-259 is, substituted with histidine, the apparent second order rate constant, (kcat/Km) for the pyrophosphate exchange reaction and the aminoacylation, reaction decreases 1,000-fold and 500-fold, respectively. Crystals soaked, with MnCl2 reveal the existence of two metal binding sites between beta-, and gamma-phosphates; these sites appear to stabilize the conformation of, the ... [(full description)]
About this StructureAbout this Structure
1KMM is a [Single protein] structure of sequence from [Escherichia coli] with HAM as [ligand]. Active as [[1]], with EC number [6.1.1.21]. Full crystallographic information is available from [OCA].
ReferenceReference
The first step of aminoacylation at the atomic level in histidyl-tRNA synthetase., Arnez JG, Augustine JG, Moras D, Francklyn CS, Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7144-9. PMID:9207058
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