Evidence suggesting that the NADPH/NADP ratio modulates the splitting of the isocitrate flux between the glyoxylic and tricarboxylic acid cycles, in Escherichia coli.
Explore the source record for details and available documents.
Citric Acid Cycle↗
Biomedical subjects
A Machado
Publications and source records attributed to A Machado.
Isocitrate dehydrogenase of Tetrahymena pyriformis.
We have studied the isocitrate dehydrogenase of Tetrahymena pyriformis. This enzyme is able to utilize both NAD and NADP, but kinetic studies suggest that the enzymatic activity with NAD is not of physiological signifance. Some of the factors that might regualte the NADP-dependent isocitrate dehydrogenase were also studied. This enzyme has an absolute requirement for divalent cations; Mg,+ and Mn2+ will serve as cofactors but the latter is more effective than the former. It is known that this enzyme is subject to a concerted inhibition by oxaloacetate and glyoxylate. Either glyoxylate or oxaloacetate alone also are capable of inhibiting the enzyme although higher concentrations are required. We have found concerted inhibition also for the NAD-dependent isocitrate dehydrogenase from rat liver and yeast. The activity of the Tetrahymena pyriformis enzyme is inhibited by NADPH. This inhibition is competitive with NADP. The Ki and Km values are, respectively, 20 micrometers and 18 micrometers.
Animals↗
The synthesis of yeast matrix mitochondrial enzymes is regulated by different levels of mitochondrial function.
Explore the source record for details and available documents.
Aerobiosis↗
Constancy of the NADP-linked isocitrate dehydrogenase/transhydrogenase ratios of mitochondria of different mammalian tissues.
Explore the source record for details and available documents.
Animals↗
Distribution of acetylcholinesterase along the dorso-ventral axis of the hippocampal formation in the rabbit.
Explore the source record for details and available documents.
Acetylcholinesterase↗
[Clinical, electrocardiographic and cineangiographic evaluation of the 1st patients submitted to myocardial revascularization surgery at the Instituto de Cardiologia do Rio Grande do Sul].
Explore the source record for details and available documents.
Cineangiography↗
Regulation of the level of yeasts citrate synthase by oxygen availability.
The activity of yeasts citrate synthase in cells grown under different hypoxic conditions has been investigated. A linear relationship between the citrate synthase activity and the respiratory capacity of the cells has been found. When Saccharomyces cerevisiae was grown on fermentable substrates the activity decreased as the concentration of sugars in the medium increased. The enzyme of the yeast Rhodoturula showed a high activity in spite of the existence of high sugar concentration in the culture medium. Neither feed-back repression by glutamate nor feed-forward induction by ammonia has been found in bakers' yeast. The results suggest that the regulation of the enzyme by oxygen availability takes place by the ""de novo'' synthesis of the enzyme.
Acetates↗