We recently showed that maize (Zea mays L.) leaves contain appreciable amounts of phosphoenolpyruvate carboxykinase (PEPCK; R.P. Walker, R.M. Acheson, L.I. Tecsi, R.C. Leegood [1997] Aust J Plant Physiol 24: 459-468). In the present study, we investigated the role of PEPCK in C4 photosynthesis in maize. PEPCK activity and protein were enriched in extracts from bundle-sheath (BS) strands compare...

The source of hyperpolarized (HP) [(13)C]bicarbonate in the liver during metabolism of HP [1-(13)C]pyruvate is uncertain and likely changes with physiology. Multiple processes including decarboxylation through pyruvate dehydrogenase or pyruvate carboxylase followed by subsequent decarboxylation via phosphoenolpyruvate carboxykinase (gluconeogenesis) could play a role. Here we tested which metab...

The enzymatic decarboxylation of n-ascorbic acid by rat kidney homogenates has been reported in an earlier study (1). It was shown that factors present in both the soluble and the particulate fractions were required for maximal activity. Evidence was presented suggesting that dehydro-L-ascorbic acid and 2,3-diketo-n-gulonic acid were intermediates in the decarboxylation of the vitamin. The reac...

INTRODUCTION Vegetable oils undergo appreciable deterioration during processing and storage. The residual free fatty acid (FFA) concentration of vegetable oils is a function of the processing and storage conditions. Vegetable oils spoilage, usually defined as rancidity, is the result of fatty acid moity has been recognized as the point of attack in peroxide formation Peroxide-forming reactions ...