1kmm: Difference between revisions
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[[Image:1kmm.gif|left|200px]]<br /> | [[Image:1kmm.gif|left|200px]]<br /><applet load="1kmm" size="450" color="white" frame="true" align="right" spinBox="true" | ||
<applet load="1kmm" size="450" color="white" frame="true" align="right" spinBox="true" | |||
caption="1kmm, resolution 2.6Å" /> | caption="1kmm, resolution 2.6Å" /> | ||
'''HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE'''<br /> | '''HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
1KMM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with HAM as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Histidine--tRNA_ligase Histidine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.21 6.1.1.21] | 1KMM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with HAM as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Histidine--tRNA_ligase Histidine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.21 6.1.1.21] Known structural/functional Sites: <scene name='pdbsite=S1A:HIS And Atp Binding Site, Product Of First Reaction (Int ...'>S1A</scene>, <scene name='pdbsite=S1B:HIS And Atp Binding Site, Product Of First Reaction (Int ...'>S1B</scene>, <scene name='pdbsite=S1C:HIS And Atp Binding Site, Product Of First Reaction (Int ...'>S1C</scene> and <scene name='pdbsite=S1D:HIS And Atp Binding Site, Product Of First Reaction (Int ...'>S1D</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1KMM OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: synthetase]] | [[Category: synthetase]] | ||
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Revision as of 17:31, 18 December 2007
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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 pyrophosphate. The use of both conserved metal ions and arginine in, phosphoryl transfer provides evidence of significant early functional, divergence of class II aminoacyl-tRNA synthetases.
About this StructureAbout this Structure
1KMM is a Single protein structure of sequence from Escherichia coli with HAM as ligand. Active as Histidine--tRNA ligase, with EC number 6.1.1.21 Known structural/functional Sites: , , and . 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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