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Query: CAS:433-48-7 (Fluoropyruvate)
 9 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pyruvate dehydrogenase complex (PDH complex) of Escherichia coli and its pyruvate dehydrogenase component (E1) are rapidly inactivated by low concentrations of fluoropyruvate in a thiamin pyrophosphate (TPP) dependent process. The inactivation rates for the PDH complex and for its E1 component are similar. Pyruvate protects the PDH complex and the E1 component against inactivation by fluoropyruvate. Dihydrolipoamide protects the E1 component from inactivation. TPP is not covalently bound to the PDH complex or to the E1 component by the inactivating reaction. When [14C]fluoropyruvate is used to inactivate the PDH complex, 14C remains bound to the complex after gel filtration. This bound radioactivity is cleaved from the protein by NH2OH, -OH, and NaBH4 but not by dilute acid. When released by -OH, greater than 90% of the 14C cochromatographs with acetate on DEAE-Sephadex. When released by NaBH4, and 14C is recovered as [14C]ethanol. Colorimetric analysis for sulfhydryl groups on the native E1 component and the inactivated E1 component, using 5,5'-dithiobis(2-nitrobenzoate), reveals that complete inactivation results from covalent modification of 1.37 +/- 0.03 sulfhydryl residues. Fluoropyruvate is known to generate acetyl-TPP at the active site of E1. The available evidence indicates that acetylation of a sulfhydryl group by acetyl-TPP at the active site of the E1 component inactivates the enzyme.
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PMID:Inactivation of the pyruvate dehydrogenase complex of Escherichia coli by fluoropyruvate. 251 3

1-Deoxy-d-xylulose 5-phosphate synthase (DXP synthase) catalyzes the thiamine diphosphate (TPP)-dependent condensation of pyruvate and d-glyceraldehyde 3-phosphate (GAP) to yield DXP in the first step of the methylerythritol phosphate pathway for isoprenoid biosynthesis. Steady-state kinetic constants for DXP synthase calculated from the initial velocities measured at varying concentrations of substrates were as follows: k(cat) = 1.9 +/- 0.1 s(-1), K(m)(GAP) = 0.068 +/- 0.001 mM, and K(m)(pyruvate) = 0.44 +/- 0.05 mM for pyruvate and GAP; k(cat) = 1.7 +/- 0.1 s(-1), K(m)(d-glyceraldehyde) = 33 +/- 3 mM, and K(m)(pyruvate) = 1.9 +/- 0.5 mM for d-glyceraldehyde and pyruvate. beta-Fluoropyruvate was investigated as a dead-end inhibitor for pyruvate. Double-reciprocal plots showed a competitive inhibition pattern with respect to pyruvate and noncompetitive inhibition with respect to GAP/d-glyceraldehyde. (14)CO(2) trapping experiments demonstrated that the binding of both substrates (pyruvate and GAP/d-glyceraldehyde) is required for the formation of a catalytically competent enzyme-substrate complex. These results are consistent with an ordered mechanism for DXP synthase where pyruvate binds before GAP/d-glyceraldehyde.
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PMID:Rhodobacter capsulatus 1-deoxy-D-xylulose 5-phosphate synthase: steady-state kinetics and substrate binding. 1254 36

Kinetic and binding studies were carried out on substrate and cofactor interaction with the pyruvate dehydrogenase complex from bovine heart. Fluoropyruvate and pyruvamide, previously described as irreversible and allosteric inhibitors, respectively, are strong competitive inhibitors with respect to pyruvate. Binding of thiamin diphosphate was used to study differences between the active dephosphorylated and inactive phosphorylated enzyme states by spectroscopic methods. The change in both the intrinsic tryptophan fluorescence and the fluorescence of the 6-bromoacetyl-2-dimethylaminonaphthalene-labelled enzyme complex produced on addition of the cofactor showed similar binding behaviour for both enzyme forms, with slightly higher affinity for the phosphorylated form. Changes in the CD spectrum, especially the negative Cotton effect at 330 nm as a function of cofactor concentration, both in the absence and presence of pyruvate, also revealed no drastic differences between the two enzyme forms. Thus, inactivation of the enzyme activity of the pyruvate dehydrogenase complex is not caused by impeding the binding of substrate or cofactor.
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PMID:Interaction of thiamin diphosphate with phosphorylated and dephosphorylated mammalian pyruvate dehydrogenase complex. 1584 42