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The fate of fluoropyruvate as an alternative substrate and inactivator of the pyruvate dehydrogenase complex of Escherichia coli

Thesis/Dissertation ·
OSTI ID:5564220
The pyruvate dehydrogenase component (E{sub 1}) of the pyruvate dehydrogenase complex of Escherichia coli catalyzes the decomposition of fluoropyruvate to CO{sub 2}, fluoride anion, and acetate. Acetyl thiamin pyrophosphate (acetyl-TPP) is an intermediate in this reaction. Incubation of the pyruvate dehydrogenase complex with ({sup 14}C)fluoropyruvate, TPP, CoASH, and either NADH or pyruvate as reducing agent leads to the formation of ({sup 14}C) acetylCoA. In this reaction the acetyl group of acetyl-TPP is partitioned by transfer to both CoASH and water. When the E{sub 1} component is incubated with ({sup 14}C)fluoropyruvate, TPP, and dihydrolipoamide, ({sup 14}C)acetyldihydrolipoamide is produced. The formation of ({sup 14}C)acetyldihydrolipoamide was examined as a function of dihydrolipoamide concentration. A plot of the extent of acetyl group-partitioning to dihydrolipoamide as a function of 1/(dihydrolipoamide) shows 95 {plus minus} 2% acetyl group transfer to dihydrolipoamide when dihydrolipoamide concentration is extrapolated to infinity. It is concluded that acetyl-TPP is chemically competent as an intermediate for the pyruvate dehydrogenase complex catalyzed oxidative decarboxylation of pyruvate.
Research Organization:
Wisconsin Univ., Madison, WI (USA)
OSTI ID:
5564220
Country of Publication:
United States
Language:
English