A previous study in this laboratory (12) indicated that leaves and excised roots of bush beans grown under conditions of Fe deficiency fixed larger quantities of C1402 from an enriched atmosphere than did those receiving adequate amounts of Fe. For this reason, studies have been made to determine the effect of Fe and chelating agents on PEP (phosphoenolpyruvate) carboxylase (1, 9, 13), PEP carb...

A method is proposed to detect whether a given enzyme catalyzes a rate-limiting step in a metabolic pathway. With the use of a range of concentrations of specific inhibitors of an enzyme, the finding of a biphasic response with an initial null effect indicates the non-rate-limiting nature of the enzyme. With this method, phosphoenolpyruvate carboxykinase is indicated to catalyze a rate-limiting...

Evidence to support an association between early nutrition and the development of obesity in the rat is equivocal. In this study we have investigated the postnatal growth, glucose tolerance, and adipocyte function of the offspring from pregnant rats fed with diets containing either 20% or 8% protein during gestation. By 25 weeks of age, the female offspring of dams fed with the diet containing ...

When rat liver cytosolic P-enolpyruvate carboxykinase is purified, its activity is no longer enhanced by incubation with 30 muM Fe2+. Ferrous ion stimulation of the purified enzyme is restored by the addition of rat liver cytosol. The agent responsible is a cytosolic protein, named P-enolpyruvate carboxykinase ferroactivator, that was readily separated from the enzyme during purification of the...

The stabilization of phosphoenolpyruvate carboxykinase mRNA by glucocorticoids appears to result from the interaction of an induced factor with an RNA element located in the 3' noncoding sequence of the mRNA. This element can confer glucocorticoid-dependent stabilization upon a heterologous mRNA, and thus strategies developed to investigate the control of mRNA transcription can now be applied t...

Rat offspring exposed to ethanol (EtOH rats) during pregnancy are insulin resistant, but it is unknown whether they have increased gluconeogenesis. To address this issue, we determined blood glucose and liver gluconeogenic genes, proteins, and enzyme activities before and after insulin administration in juvenile and adult EtOH rats and submitted adult EtOH rats to a pyruvate challenge. In juven...

1. Phosphoenolpyruvate carboxykinase was assayed by three methods: (i) incorporation of H(14)CO(3) (-) into oxaloacetate: (ii) conversion of oxaloacetate into phosphoenolpyruvate, subsequently assayed enzymically; and (iii) transfer of (32)P from [gamma-(32)P]GTP to oxaloacetate. 2. Enzyme activity is increased in liver and epididymal adipose tissue in alloxan-diabetes and starvation, and in ki...