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| {{STRUCTURE_2ji7| PDB=2ji7 | SCENE= }} | | {{STRUCTURE_2ji7| PDB=2ji7 | SCENE= }} |
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| '''X-RAY STRUCTURE OF OXALYL-COA DECARBOXYLASE WITH COVALENT REACTION INTERMEDIATE'''
| | ===X-RAY STRUCTURE OF OXALYL-COA DECARBOXYLASE WITH COVALENT REACTION INTERMEDIATE=== |
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| ==Overview==
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| Despite more than five decades of extensive studies of thiamin diphosphate (ThDP) enzymes, there remain many uncertainties as to how these enzymes achieve their rate enhancements. Here, we present a clear picture of catalysis for the simple nonoxidative decarboxylase, oxalyl-coenzyme A (CoA) decarboxylase, based on crystallographic snapshots along the catalytic cycle and kinetic data on active site mutants. First, we provide crystallographic evidence that, upon binding of oxalyl-CoA, the C-terminal 13 residues fold over the substrate, aligning the substrate alpha-carbon for attack by the ThDP-C2 atom. The second structure presented shows a covalent reaction intermediate after decarboxylation, interpreted as being nonplanar. Finally, the structure of a product complex is presented. In accordance with mutagenesis data, no side chains of the enzyme are implied to directly participate in proton transfer except the glutamic acid (Glu-56), which promotes formation of the 1',4'-iminopyrimidine tautomer of ThDP needed for activation.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17637344}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17637344 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17637344}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Thiamin diphosphate-dependent]] | | [[Category: Thiamin diphosphate-dependent]] |
| [[Category: Thiamine pyrophosphate]] | | [[Category: Thiamine pyrophosphate]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 08:57:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 23:27:40 2008'' |