A number of metabolic factors and the activity of a number of enzymes were determined in meal-fed (animals fed a single daily 2 hr meal) and nibbling (ad libitum-fed) rats. The dependency of the observed adaptive changes on the ingestion of carbohydrate was studied by feeding diets high in carbohydrate or fat. Glucose-6-phosphate dehydrogenase and NADP-malic dehydrogenase were more active in ad...

The quantum yield for CO(2) uptake was measured on a number of C(3) and C(4) monocot and dicot species. Under normal atmospheric conditions (330 microliters per liter CO(2), 21% O(2)) and a leaf temperature of 30 degrees C, the average quantum yields (moles CO(2) per einstein) were as follows: 0.052 for C(3) dicots, 0.053 for C(3) grasses, 0.053 for NAD-malic enzyme type C(4) dicots, 0.060 for ...

In the previous communication (l), it was shown that the free energy of the bivalent fumarate ion at 25” is -144,630 calories. In the present communication the measurement of the equilibrium at 25” between fumaric acid and malic acid in the presence of fumarase is reported, and from the values obtained computations are made of the free energy and heat of formation of the bivalent I-malate ion a...

Whey protein isolate and glycerol were mixed to form a matrix to incorporate antimicrobial agents and produce edible films with antimicrobial activity against Listeria monocytogenes strains isolated from cheeses. Various organic acids were used to decrease pH down to approximately 3. In a preliminary assay without nisin, the effect of each organic acid was evaluated with respect to the rheologi...

The concentration of glucan, mucilage, soluble carbohydrates, and malic acid were determined in Opuntia bigelovii Engelm. during a 23-week period. The experiment began during the dry summer by irrigation to stimulate Crassulacean acid metabolism and was followed by 13 weeks of drought. After the 13-week drought period, the plants were irrigated throughout a 10-week period until late December. T...

The Berberis vulgaris (BV) plant has been extensively used as a traditional medicine in some part of Asian region especially in Western Asia. The BV fruits is claimed also to have anti-viral activities, and as a treatment for chronic candidiasis, indigestion and parasites. The present study was conducted to evaluate the antioxidative activity, nutritional and antinutritional composition of Berb...

The competitive inhibition of malic dehydrogenase by /3-fluorooxaloacetate has been reported by Kun et al. (1). In addition to its inhibitory effect, /3-fluoro-oxaloacetate also oxidized reduced diphosphopyridine nucleotide enzymatically, but at a rate only 0.02% that of oxaloacetate. It was also shown (2) that fi-fluorooxaloacetate was a competitive inhibitor of glutamic-aspartic transaminase,...

Increased dietary protein intake rapidly (3 h) decreases hepatic malic enzyme and increases hepatic histidase mRNA expression in broiler chicks. A series of experiments was conducted to determine the role that glucagon or a specific mixture of dietary amino acids might have in regulating the rapid changes in mRNA expression of these enzymes, when dietary protein intake is increased. Three hours...

The cytosolic malic enzyme from the pigeon liver is sensitive to chemical denaturant urea. When monitored by protein intrinsic fluorescence or circular dichroism spectral changes, an unfolding of the enzyme in urea at 25 degrees C and pH 7.4 revealed a biphasic phenomenon with an intermediate state detected at 4-5 m urea. The enzyme activity was activated by urea up to 1 m but was completely lo...

Pyruvate, a precursor for several amino acids, can be synthesized from phosphoenolpyruvate by pyruvate kinase. Nevertheless, pyk1 pyk2 mutants of Saccharomyces cerevisiae devoid of pyruvate kinase activity grew normally on ethanol in defined media, indicating the presence of an alternative route for pyruvate synthesis. A candidate for this role is malic enzyme, which catalyzes the oxidative dec...