Human and rat erythrocytes were fractionated by counter-current distribution in charge-sensitive dextran/poly(ethylene glycol) two-phase systems. The specific activities of the key glycolytic enzymes (hexokinase, phosphofructokinase and pyruvate kinase) declined along the distribution profiles, although the relative positions of the activity profiles were reversed in the two species. These enzy...

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...

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...

A 32P-labeled pyruvate kinase (L-type isozyme) was elicited in response to glucagon and has been isolated from suspensions of hepatocytes incubated with inorganic [32P]phosphate. The pyruvate kinase in crude extracts of hepatocytes was stabilized by ammonium sulfate fractionation, 30% glycerol, and 50 mM KF and the enzyme was isolated by immunoprecipitation with anti-liver pyruvate kinase immun...

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 relative rate of pyruvate kinase synthesis in alloxan-diabetic rats was Y3 of that observed in controls and increased 3to 4-fold upon treatment with insulin for 3 days. Similar changes in the catalytic activity were observed: 120 + 40, 650 + 100, and 230 ± 79 units of pyruvate kinase/liver in diabetic rats, diabetic rats maintained on insulin for 3 days, and controls, respectively. Thus, ch...

Pyruvate kinase (EC 2.7.1.40) is one of the key regulatory enzymes controlling glycolysis in plants and animals. It catalyzes the irreversible formation of pyruvate and ATP from phosphoenolpyruvate and ADP. In plants, pyruvate kinases can be either heteroor homotetramers depending on the source of the isozyme (Plaxton, 1989). Pyruvate kinase enzymes have been purified or partially purified from...

The regulatory effects of alpha-ketoisovalerate on purified bovine heart pyruvate dehydrogenase complex and endogenous pyruvate dehydrogenase kinase were investigated. Incubation of pyruvate dehydrogenase complex with 0.125 to 10 mM alpha-ketoisovalerate caused an initial lag in enzymatic activity, followed by a more linear but inhibited rate of NADH production. Incubation with 0.0125 or 0.05 m...

Pyruvate kinase is an enzyme that catalyzes the conversion of phosphoenolpyruvate and ADP to pyruvate and ATP in glycolysis and plays a role in regulating cell metabolism. There are four mammalian pyruvate kinase isoforms with unique tissue expression patterns and regulatory properties. The M2 isoform of pyruvate kinase (PKM2) supports anabolic metabolism and is expressed both in cancer and nor...