[U-13C]glutamate metabolism in rat brain mitochondria reveals malic enzyme activity

Bakken, Inger J. and Sonnewald, Ursula and Clark, John B. and Bates, Timothy E. (1997) [U-13C]glutamate metabolism in rat brain mitochondria reveals malic enzyme activity. Neuroreport, 8 (7). pp. 1567-1570. ISSN 0959-4965

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Abstract

13C nuclear magnetic resonance spectroscopy was used to study the activity of malic enzyme in isolated brain mitochondria from rat in the presence of unlabelled malate and [U-13C]glutamate. ADP, inorganic phosphate, malate and [U-13C]glutamate were added to a suspension of oxygenated mitochondria. Typical tricarboxylic acid (TCA) cycle constituents (malate, 2-oxoglutarate and succinate) were labelled from [U-13C]glutamate and detected in the superfusion medium. The labelling patterns in the different atom positions of glutamate revealed entry of both unlabelled and labelled acetyl-CoA into the TCA cycle. Unlabelled acetyl-CoA was derived via pyruvate from exogenously applied malate by the action of mitochondrial malic enzyme, while labelled acetyl-CoA was derived from TCA cycle intermediates, most likely by the action of mitochondrial malic enzyme on malate produced from [U-13C]glutamate. The results demonstrate malic enzyme activity and pyruvate recycling in isolated rat brain mitochondria.

Item Type:Article
Additional Information:13C nuclear magnetic resonance spectroscopy was used to study the activity of malic enzyme in isolated brain mitochondria from rat in the presence of unlabelled malate and [U-13C]glutamate. ADP, inorganic phosphate, malate and [U-13C]glutamate were added to a suspension of oxygenated mitochondria. Typical tricarboxylic acid (TCA) cycle constituents (malate, 2-oxoglutarate and succinate) were labelled from [U-13C]glutamate and detected in the superfusion medium. The labelling patterns in the different atom positions of glutamate revealed entry of both unlabelled and labelled acetyl-CoA into the TCA cycle. Unlabelled acetyl-CoA was derived via pyruvate from exogenously applied malate by the action of mitochondrial malic enzyme, while labelled acetyl-CoA was derived from TCA cycle intermediates, most likely by the action of mitochondrial malic enzyme on malate produced from [U-13C]glutamate. The results demonstrate malic enzyme activity and pyruvate recycling in isolated rat brain mitochondria.
Keywords:mitochondria, Brain, malic enzyme, 13C, NMR Spectroscopy
Subjects:C Biological Sciences > C730 Metabolic Biochemistry
A Medicine and Dentistry > A100 Pre-clinical Medicine
B Subjects allied to Medicine > B140 Neuroscience
Divisions:College of Science > School of Life Sciences
ID Code:5317
Deposited By: Timothy Bates
Deposited On:11 Jun 2012 09:54
Last Modified:11 Jun 2012 09:54

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