In pancreatic beta-cells, methyl pyruvate is a potent secretagogue and is widely used to study stimulus-secretion coupling. In contrast with pyruvate, which barely stimulates insulin secretion, methyl pyruvate was suggested to act as an effective mitochondrial substrate. We show that methyl pyruvate elicited electrical activity in the presence of 0.5 mM glucose, in contrast with pyruvate. Accor...

1. Isolated rat epididymal fat-cell mitochondria showed an inverse relationship between ATP content and pyruvate dehydrogenase activity consistent with competitive inhibition of pyruvate dehydrogenase kinase by ADP. At constant ATP concentration pyruvate rapidly activated pyruvate dehydrogenase in fat-cell mitochondria, an observation consistent with inhibition of fat-cell pyruvate dehydrogenas...

The pyruvate oxidation factor (POF) is required by Streptococcus faecalis, strain 1OC1, in order to oxidize pyruvate to acetate and CO2 using oxygen or another molecule of pyruvate as the oxidant (O'Kane and Gunsalus, 1947, 1948). In order to gain some insight into the role of pyruvate oxidation factor other pyruvate reactions and acetate-producing reactions are being examined. No reliable meth...

Glucose confers acid resistance on exponentially growing bacteria by repressing formation of the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex and consequently activating acid resistance genes. Therefore, in a glucose-rich growth environment, bacteria are capable of resisting acidic stresses due to low levels of cAMP-CRP. Here we reveal a second mechanism for glucose-conferred acid resi...

PROBLEM Emerging evidence suggests that metabolism influences immune cell signaling and immunoregulation. To examine the immunoregulatory role of glycolysis in pregnancy, we evaluated the properties of pyruvate kinase in leukocytes from non-pregnant women and those with normal pregnancy and pre-eclampsia. METHOD OF STUDY We evaluated pyruvate kinase expression in lymphocytes and neutrophils f...

Pyruvate has been shown to both stimulate and inhibit kidney pyruvate dehydrogenase, (PDH,) kinase activity. The present study investigates the inhibitory effect of pyruvate under conditions in which the stimulatory effect is invariant. Inhibition of PDH, kinase activity by dichloroacetate, a pyruvate analog, is also characterized. Both pyruvate and dichloroacetate are uncompetitive, hyperbolic...

The goal of this study was to measure flux through pyruvate carboxylation and decarboxylation in the heart in vivo. These rates were measured in the anterior wall of normal anesthetized swine hearts by infusing [U-(13)C(3)]lactate and/or [U-(13)C(3)] pyruvate into the left anterior descending (LAD) coronary artery. After 1 h, the tissue was freeze-clamped and analyzed by gas chromatography-mass...

The effects of &adrenergic agonists (e.g. epinephrine and isoproterenol) on the metabolic flux through, and the activation state of the pyruvate dehydrogenase multienzyme complex, were investigated in the isolated perfused rat heart. Infusion of epinephrine caused an inhibition of pyruvate decarboxylation at low (0.1 m ~ ) pyruvate concentrations in the perfusion medium, a stimulation of flux a...

In the present research, synthesis of butyl oleate ester from oleic acid and butanol using loofa-immobilized Rhizopus oryzae as a whole cell biocatalyst (LIC) was studied in which hexane was used as the hydrophobic solvent. Decrease of mass transfer limitations as result of the interface formation between the two immiscible substrates, positively affected on the reaction progress (87% as the es...

1. The proportion of active (dephosphorylated) pyruvate dehydrogenase in perfused rat heart was decreased by alloxan-diabetes or by perfusion with media containing acetate, n-octanoate or palmitate. The total activity, of the dehydrogenase was unchanged. 2. Pyruvate (5 or 25mm) or dichloroacetate (1m) increased the proption of active (dephosphorylated) pyruvate debydrogenase in perfused rat hea...