Publication Date:
2001-12-26
Description:
In anaerobic organisms, the decarboxylation of pyruvate, a crucial component of intermediary metabolism, is catalyzed by the metalloenzyme pyruvate: ferredoxin oxidoreductase (PFOR) resulting in the generation of low potential electrons and the subsequent acetylation of coenzyme A (CoA). PFOR is the only enzyme for which a stable acetyl thiamine diphosphate (ThDP)-based free radical reaction intermediate has been identified. The 1.87 A-resolution structure of the radical form of PFOR from Desulfovibrio africanus shows that, despite currently accepted ideas, the thiazole ring of the ThDP cofactor is markedly bent, indicating a drastic reduction of its aromaticity. In addition, the bond connecting the acetyl group to ThDP is unusually long, probably of the one-electron type already described for several cation radicals but not yet found in a biological system. Taken together, our data, along with evidence from the literature, suggest that acetyl-CoA synthesis by PFOR proceeds via a condensation mechanism involving acetyl (PFOR-based) and thiyl (CoA-based) radicals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chabriere, E -- Vernede, X -- Guigliarelli, B -- Charon, M H -- Hatchikian, E C -- Fontecilla-Camps, J C -- New York, N.Y. -- Science. 2001 Dec 21;294(5551):2559-63.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Cristallographie et Cristallogenese des Proteines, Institut de Biologie Structurale Jean-Pierre Ebel, Commissariat a l'Energie Atomique, Universite Joseph Fourier, CNRS, 41, rue Jules Horowitz, 38027 Grenoble Cedex 1, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11752578" target="_blank"〉PubMed〈/a〉
Keywords:
Acetyl Coenzyme A/metabolism
;
Anaerobiosis
;
Binding Sites
;
Carbon Dioxide/metabolism
;
Catalysis
;
Chemistry, Physical
;
Coenzymes/*chemistry/metabolism
;
Crystallization
;
Crystallography, X-Ray
;
Desulfovibrio/*enzymology
;
Dimerization
;
Electron Spin Resonance Spectroscopy
;
*Free Radicals/chemistry/metabolism
;
Ketone Oxidoreductases/*chemistry/metabolism
;
Molecular Conformation
;
Molecular Structure
;
Oxidation-Reduction
;
Physicochemical Phenomena
;
Protein Conformation
;
Pyruvate Synthase
;
Pyruvic Acid/metabolism
;
Thiamine Pyrophosphate/*chemistry/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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