The endogenous citric acid-cycle intermediates and amino acids of mitochondria

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Abstract
Washed mitochondria were extracted and analysed for citric acid-cycle intermediates. Endogenous glutamic acid and aspartic acid were also determined. No endogenous citric acid-cycle intermediates were found in mitochondria from pigeon brain, locust-head tissue and the muscle of rat, pigeon, frog and earthworm (detection limit about 0[center dot]2 [mu]mole/g. dry wt.). Citrate was found in mitochondria from lobster hepatopancreas, pigeon and rat liver and locust thoracic muscle (2, 4, 5 and 15 [mu]moles/g. respec-tively). Fumarate, [alpha]-oxoglutarate and succinate were found in other types of mitochondria (range 0[center dot]4[long dash]1[center dot]4 [mu]moles/g.). All mitochondria contained glutamate and aspartate (1-70 [mu]moles/g.). In some types of mitochondria glutamate and aspartate accounted for over 70% of the free [alpha]-amino acid nitrogen. Mitochondria from nervous tissue also contained glutamine. Experiments on the endogenous respiration of brain mitochondria indicated that amino acid oxidation was responsible for the endogenous oxygen uptake.