1kmn
From Proteopedia
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HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDINOL AND ATP
Overview
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 Structure
1KMN is a [Single protein] structure of sequence from [Escherichia coli] with HSO and ATP as [ligands]. Active as [Histidine--tRNA ligase], with EC number [6.1.1.21]. Structure known Active Sites: S1A, S1B, S1C and S1D. Full crystallographic information is available from [OCA].
Reference
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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