1kmm: Difference between revisions

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[[Image:1kmm.~~gif~~|left|200px]]

[[Image:1kmm.png|left|200px]]

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~~'''~~HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE~~'''~~

===HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE===

~~==Overview==~~

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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.

The line below this paragraph, {{ABSTRACT_PUBMED_9207058}}, adds the Publication Abstract to the page

(as it appears on PubMed at http://www.pubmed.gov), where 9207058 is the PubMed ID number.

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==About this Structure==

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[[Category: Ligase]]

[[Category: Synthetase]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on ~~Fri May~~ 2 22:55:10 2008''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 10:33:37 2008''

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-[[Image:1kmm.gif|left|200px]]
+{{Seed}}
+[[Image:1kmm.png|left|200px]]
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 {{STRUCTURE_1kmm|  PDB=1kmm  |  SCENE=  }}
-'''HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE'''
+===HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDYL-ADENYLATE===
-==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 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.
+The line below this paragraph, {{ABSTRACT_PUBMED_9207058}}, adds the Publication Abstract to the page
+(as it appears on PubMed at http://www.pubmed.gov), where 9207058 is the PubMed ID number.
+-->
+{{ABSTRACT_PUBMED_9207058}}
 ==About this Structure==
@@ Line 29: / Line 33: @@
 [[Category: Ligase]]
 [[Category: Synthetase]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 22:55:10 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul  2 10:33:37 2008''