1gpu: Difference between revisions
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[[Image:1gpu.gif|left|200px]]<br /> | [[Image:1gpu.gif|left|200px]]<br /><applet load="1gpu" size="450" color="white" frame="true" align="right" spinBox="true" | ||
<applet load="1gpu" size="450" color="white" frame="true" align="right" spinBox="true" | |||
caption="1gpu, resolution 1.86Å" /> | caption="1gpu, resolution 1.86Å" /> | ||
'''TRANSKETOLASE COMPLEX WITH REACTION INTERMEDIATE'''<br /> | '''TRANSKETOLASE COMPLEX WITH REACTION INTERMEDIATE'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
1GPU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with CA and THD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Transketolase Transketolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.1 2.2.1.1] | 1GPU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with CA and THD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Transketolase Transketolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.1 2.2.1.1] Known structural/functional Site: <scene name='pdbsite=AC1:Thd Binding Site For Chain B'>AC1</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1GPU OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: transferase(ketone residues)]] | [[Category: transferase(ketone residues)]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Dec 18 15:29:19 2007'' | ||
Revision as of 16:19, 18 December 2007
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TRANSKETOLASE COMPLEX WITH REACTION INTERMEDIATE
OverviewOverview
Kinetic and spectroscopic data indicated that addition of the donor, substrate hydroxypyruvate to the thiamin diphosphate (ThDP)-dependent, enzyme transketolase (TK) led to the accumulation of the, alpha-carbanion/enamine of (alpha,beta-dihydroxyethyl) ThDP, the key, reaction intermediate in enzymatic thiamin catalysis. The, three-dimensional structure of this intermediate trapped in the active, site of yeast TK was determined to 1.9-A resolution by using, cryocrystallography. The electron density suggests a planar, alpha-carbanion/enamine intermediate having the E-configuration. The, reaction intermediate is firmly held in place through direct hydrogen, bonds to His-103 and His-481 and an indirect hydrogen bond via a water, molecule to His-69. The 4-NH(2) group of the amino-pyrimidine ring of ThDP, is within 3 A distance to the alpha-hydroxy oxygen atom of the, dihydroxyethyl moiety but at an angle unfavorable for a strong hydrogen, bond. No structural changes occur in TK on formation of the reaction, intermediate, suggesting that the active site is poised for catalysis and, conformational changes during the enzyme reaction are not very likely. The, intermediate is present with high occupancy in both active sites, arguing, against previous proposals of half-of-the-sites reactivity in yeast TK.
About this StructureAbout this Structure
1GPU is a Single protein structure of sequence from Saccharomyces cerevisiae with CA and THD as ligands. Active as Transketolase, with EC number 2.2.1.1 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Snapshot of a key intermediate in enzymatic thiamin catalysis: crystal structure of the alpha-carbanion of (alpha,beta-dihydroxyethyl)-thiamin diphosphate in the active site of transketolase from Saccharomyces cerevisiae., Fiedler E, Thorell S, Sandalova T, Golbik R, Konig S, Schneider G, Proc Natl Acad Sci U S A. 2002 Jan 22;99(2):591-5. Epub 2002 Jan 2. PMID:11773632
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