Extracts of Klebsiella pneumoniae oxidatively convert 1-phospho-5-S-methylthioribose (1-PMTR) to alpha-keto-gamma-methylthiobutyrate, a precursor of methionine, and to S-methylthiopropionate and formate. One equivalent of formate is produced per equivalent of alpha-keto-gamma-methylthiobutyrate and two equivalents of formate per equivalent of methylthiopropionate. Two compounds were identified ...

The major objective of this work has been to learn the effect of plague toxin on several enzymatic systems in vitro. The availability of purified preparations of plague toxin (Ajl et al., 1955) permitted us to carry out these investigations. In this report, experiments are described in which purified plague toxin has been added to actively respiring cell-free extracts and crude mouse liver homo...

BACKGROUND Hexuronic acids such as D-galacturonic acid and D-glucuronic acid can be utilized via different pathways within the metabolism of microorganisms. One representative, the oxidative pathway, generates α-keto-glutarate as the direct link entering towards the citric acid cycle. The penultimate enzyme, keto-deoxy glucarate dehydratase/decarboxylase, catalyses the dehydration and decarboxy...

AIMS An increasing number of clinical studies highlight the importance of the inflammatory mediator prostaglandin F2 α (PGF(2α)). Prostaglandin F2 α activity has been suggested to play pivotal roles in the development of cardiovascular diseases and cancer. However, whether systemic PGF(2α) concentrations may signal mortality is unknown. The aim was to evaluate in vivo PGF(2α) formation, by meas...

Rigorous alkaline hydrolysis of the two primary (cholic and chenodeoxycholic) and of the two preponderant secondary (deoxycholic and lithocholic) bile acids found in bile led to excellent recoveries. Such was not the case with 11 different keto bile acid standards. Recoveries for a number of standards were unacceptably low and a variety of artefactural products were tentatively identified by ga...

The dynamic kinetic resolution of β-halo α-keto esters via an asymmetric cross-benzoin reaction is described. A chiral N-heterocyclic carbene catalyzes the umpolung addition of aldehydes to racemic α-keto esters. The resulting fully substituted β-halo glycolic ester products are obtained with high levels of enantio- and diastereocontrol. The high chemoselectivity observed is a result of greater...

Evidence is presented that aromatic ol-keto acid reductase accounts for at least 80% of the total activity responsible for the reduction of aromatic a-keto acids to their corresponding phenyllactic acids in mammalian tissues. The remaining activity can be attributed to lactic dehydrogenase, which is in keeping with the known broad substrate specificity of this enzyme. The relative contribution ...

Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a deficiency in branched chain alpha-keto acid dehydrogenase that can result in neurodegenerative sequelae in human infants. In the present study, increased concentrations of MSUD metabolites, in particular alpha-keto isocaproic acid, specifically induced apoptosis in glial and neuronal cells in culture. Apoptosis was a...

New Schiff bases derived from 2-aminopyridene and 2-aminopyrazine have been synthesized. The UV-Visible spectra of the compounds have been investigated in acetonitrile and toluene. The compounds were in tautomeric equilibrium (enol-imine O- H...N, keto-amine O...H-N forms) in polar and nonpolar solvents. For some derivatives the keto-amine form was observed in both toluene and acetonitrile. 1H-...