THE HETEROGENEITY OF RAT BRAIN MITOCHONDRIA ISOLATED ON CONTINUOUS SUCROSE GRADIENTS1
- 1 February 1969
- journal article
- Published by Wiley in Journal of Neurochemistry
- Vol. 16 (2) , 225-234
- https://doi.org/10.1111/j.1471-4159.1969.tb05940.x
Abstract
Abstract— The distribution of a series of enzymes in the post‐nuclear supernatant of rat brain homogenates was investigated following continuous density‐gradient centrifugation. The enzymes studied were acetyl coenzyme A synthetase, glutamic dehydrogenase, glutamine synthetase, glutaminase I, succinic dehydrogenase and monoamine oxidase. Each of these enzymes with the exception of glutamine synthetase appears predominantly in the mitochondrial region of the gradient. Although about 20 per cent of this enzyme is present in the crude mitochondrial pellet, on density gradient centrifugation no special association of glutamine synthetase with any of the mitochondrial fractions was observed. Each of the other enzymes studied was found to have a characteristic distribution in the gradient; this suggests that brain mitochondria may be heterogeneous both in buoyant density and in their enzyme content. Three principal fractions are described: (i) dense particles containing high concentrations of acetyl coenzyme A synthetase and glutamic dehydrogenase; (ii) a fraction comprising the bulk of the mitochondria with high levels of monoamine oxidase, succinic dehydrogenase and glutaminase I; and (iii) particles in the synaptic ending region of the gradient characterized by relatively high levels of monoamine oxidase and succinic dehydrogenase and containing only small amounts of the other enzymes studied.If the mitochondrial heterogeneity that is observed on centrifugation reflects the existence within brain cells of mitochondria with specialized function, a partial explanation may be available for multiple pools of tricarboxylic acid cycle intermediates which have been postulated from isotopie labelling experiments.Keywords
This publication has 25 references indexed in Scilit:
- SUBCELLULAR DISTRIBUTION OF ACETYL‐CoA SYNTHETASE, ATP CITRATE LYASE, CITRATE SYNTHASE, CHOLINE ACETYLTRANSFERASE, FUMARATE HYDRATASE AND LACTATE DEHYDROGENASE IN MAMMALIAN BRAIN TISSUEJournal of Neurochemistry, 1967
- PRECURSORS IN VIVO OF GLUTAMATE, ASPARTATE AND THEIR DERIVATIVES OF RAT BRAINJournal of Neurochemistry, 1966
- MORPHOLOGICAL AND BIOCHEMICAL CORRELATES OF CEREBRAL MICROSOMES–II. *†Journal of Neurochemistry, 1966
- On the contribution of the tricarboxylic acid cycle to the synthesis of glutamate, glutamine and aspartate in brainBiochemical and Biophysical Research Communications, 1966
- INTRACELLULAR LOCALIZATION OF GLUTAMATE DECARBOXYLASE, γ‐AMINOBUTYRATE TRANSAMINASE AND SOME OTHER ENZYMES IN BRAIN TISSUEJournal of Neurochemistry, 1965
- SUBCELLULAR DISTRIBUTION OF THE ENZYMES OF THE GLUTAMIC ACID, GLUTAMINE AND γ‐AMINOBUTYRIC ACID CYCLES IN RAT BRAIN*Journal of Neurochemistry, 1965
- On the biosynthesis of acetyl coenzyme a in the brain: I. The enzymic formation of acetyl coenzyme a from acetate. Adenosine triphosphate and coenzyme ABiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1965
- MICRODETERMINATION OF MONOAMINE OXIDASE AND 5‐HYDROXYTRYPTOPHAN DECARBOXYLASE ACTIVITIES IN NERVOUS TISSUESJournal of Neurochemistry, 1965
- Peptide bound flavins and succinic dehydrogenase activity in the brainBiochemical and Biophysical Research Communications, 1964
- Enzymes of glutamine metabolism in the developing chick embryo. A study of glutamotransferase and glutamine synthetaseJournal of Experimental Zoology, 1954