1g4e: Difference between revisions

Revision as of 17:07, 2 May 2008

THIAMIN PHOSPHATE SYNTHASE

OverviewOverview

Thiamin phosphate synthase catalyzes the formation of thiamin phosphate from 4-amino-5-(hydroxymethyl)-2-methylpyrimidine pyrophosphate and 5-(hydroxyethyl)-4-methylthiazole phosphate. Several lines of evidence suggest that the reaction proceeds via a dissociative mechanism. The previously determined crystal structure of thiamin phosphate synthase in complex with the reaction products, thiamin phosphate and magnesium pyrophosphate, provided a view of the active site and suggested a number of additional experiments. We report here seven new crystal structures primarily involving crystals of S130A thiamin phosphate synthase soaked in solutions containing substrates or products. We prepared S130A thiamin phosphate synthase with the intent of characterizing the enzyme-substrate complex. Surprisingly, in three thiamin phosphate synthase structures, the active site density cannot be modeled as either substrates or products. For these structures, the best fit to the electron density is provided by a model that consists of independent pyrimidine, pyrophosphate, and thiazole phosphate fragments, consistent with a carbenium ion intermediate. The resulting carbenium ion is likely to be further stabilized by proton transfer from the pyrimidine amino group to the pyrophosphate to give the pyrimidine iminemethide, which we believe is the species that is observed in the crystal structures.

About this StructureAbout this Structure

1G4E is a Single protein structure of sequence from Bacillus subtilis. Full crystallographic information is available from OCA.

ReferenceReference

Structural characterization of the enzyme-substrate, enzyme-intermediate, and enzyme-product complexes of thiamin phosphate synthase., Peapus DH, Chiu HJ, Campobasso N, Reddick JJ, Begley TP, Ealick SE, Biochemistry. 2001 Aug 28;40(34):10103-14. PMID:11513589 Page seeded by OCA on Fri May 2 17:07:27 2008

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OCA

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 [[Image:1g4e.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 1g4e |SIZE=350|CAPTION= <scene name='initialview01'>1g4e</scene>, resolution 1.60&Aring;
+The line below this paragraph, containing "STRUCTURE_1g4e", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND=
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Thiamine-phosphate_diphosphorylase Thiamine-phosphate diphosphorylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.3 2.5.1.3] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE= THIC ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1423 Bacillus subtilis])
+-->
-|DOMAIN=
+{{STRUCTURE_1g4e|  PDB=1g4e  |  SCENE=  }}
-|RELATEDENTRY=[[2tps|2TPS]]
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1g4e FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1g4e OCA], [http://www.ebi.ac.uk/pdbsum/1g4e PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1g4e RCSB]</span>
-}}
 '''THIAMIN PHOSPHATE SYNTHASE'''
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 [[Category: Peapus, D H.]]
 [[Category: Reddick, J J.]]
-[[Category: thiamin biosynthesis]]
+[[Category: Thiamin biosynthesis]]
-[[Category: tim barrel]]
+[[Category: Tim barrel]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 17:07:27 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 20:36:25 2008''