1KEK image
Entry Detail
PDB ID:
1KEK
Keywords:
Title:
Crystal Structure of the Free Radical Intermediate of Pyruvate:Ferredoxin Oxidoreductase
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2001-11-16
Release Date:
2001-12-21
Method Details:
Experimental Method:
Resolution:
1.90 Å
R-Value Free:
0.22
R-Value Work:
0.17
R-Value Observed:
0.17
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Pyruvate-Ferredoxin Oxidoreductase
Chain IDs:A, B
Chain Length:1231
Number of Molecules:2
Biological Source:Desulfovibrio africanus
Primary Citation
Crystal structure of the free radical intermediate of pyruvate:ferredoxin oxidoreductase.
Science 294 2559 2563 (2001)
PMID: 11752578 DOI: 10.1126/science.1066198

Abstact

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.

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