Pyruvate dehydrogenase and 3-fluoropyruvate: chemical competence of 2-acetylthiamin pyrophosphate as an acetyl group donor to dihydrolipoamide
The pyruvate dehydrogenase component (E1) of the pyruvate dehydrogenase complex catalyzes the decomposition of 3-fluoropyruvate to CO/sub 2/, fluoride anion, and acetate. Acetylthiamin pyrophosphate (acetyl-TPP) is an intermediate in this reaction. Incubation of the pyruvate dehydrogenase complex with 3-fluoro(1,2-/sup 14/)pyruvate, TPP, coenzyme A (CoASH), and either NADH or pyruvate as reducing systems leads to the formation of (/sup 14/)acetyl-CoA. In this reaction the acetyl group of acetyl-TPP is partitioned by transfer to both CoASH (87 +/- 2%) and water (13 +/- 2%). When the E1 component is incubated with 3-fluoro(1,2-/sup 14/)pyruvate, TPP, and dihydrolipoamide, (/sup 14/)acetyldihydrolipoamide is produced. The formation of (14C)acetyldihydrolipoamide was examined as a function of dihydrolipoamide concentration (0.25-16 mM). A plot of the extent of acetyl group partitioning to dihydrolipoamide as a function of 1/(dihydrolipoamide) showed 95 +/- 2% acetyl group transfer to dihydrolipoamide when dihydrolipoamide concentration was 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:
- Institute for Enzyme Research, Madison, WI
- OSTI ID:
- 6764182
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 20; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECARBOXYLATION
DECOMPOSITION
ENZYMES
ISOTOPE APPLICATIONS
KETO ACIDS
KINETICS
LABELLED COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PYROPHOSPHATES
PYRUVIC ACID
REACTION KINETICS
TRACER TECHNIQUES