Fat-cells were prepared from rat and guinea-pig epididymal adipose tissue and compared on the basis of the intracellular distributions and activities of enzymes and with respect to their utilization of various U-(14)C-labelled substrates for lipogenesis. 1. Compared with the rat, guinea-pig extramitochondrial enzyme activities differed in that aconitate hydratase, alanine aminotransferase, ATP-...

Leucine and monomethyl succinate initiate insulin release, and glutamine potentiates leucine-induced insulin release. Alanine enhances and malate inhibits leucine plus glutamine-induced insulin release. The insulinotropic effect of leucine is at least in part secondary to its ability to activate glutamate oxidation by glutamate dehydrogenase (Sener, A., Malaisse-Lagae, F., and Malaisse, W. J. (...

A method has been developed whereby a fraction of rat brain mitochondria (synaptic mitochondria) was isolated from synaptosomes. This brain mitochondrial fraction was compared with the fraction of "free" brain mitochondria (non-synaptic) isolated by the method of Clark & Nicklas (1970). (J. Biol. Chem. 245, 4724-4731). Both mitochondrial fractions are shown to be relatively pure, metabolically ...

Lactate dehydrogenase (LDH) is present in the amitochondriate parasitic protist Trichomonas vaginalis and some but not all other trichomonad species. The derived amino acid sequence of T. vaginalis LDH (TvLDH) was found to be more closely related to the cytosolic malate dehydrogenase (MDH) of the same species than to any other LDH. A key difference between the two T. vaginalis sequences was tha...

There are five oxidative steps involved in the conversion of pyruvate into carbon dioxide and water in the tricarboxylic acid cycle; four of these steps lead to the reduction of nicotinamide nucleotide coenzyme more or less directly. The step catalysed by the succinate dehydrogenase results in the 'energy-linked' reduction of nicotinamide nucleotide coenzyme, under certain conditions (Chance & ...

A series of experiments, with Secale cereale and Triticum aestivum var Argee, to evaluate critically the ability of a malate/aspartate shuttle to provide reducing equivalents to drive hydroxypyruvate reduction to glycerate led to the conclusion that the shuttle, as previously envisioned, does not supply NADH to the peroxisomal matrix. First, analysis of coupled malate dehydrogenase and glutamat...

Kinetics of triiodothyronine (T3) induced changes were studied in cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH) and lactate dehydrogenase (LDH) of the liver and skeletal muscle of a catfish, Clarias batrachus. The rates of gradual inductions in the activities of all the three metabolic enzymes were faster in skeletal muscle than those of the liver. These tim...

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