Adenine Nucleotide Regulation of Malate Oxidation in Isolated Mung Bean Hypocotyl Mitochondria

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Abstract
The effects of ATP and ADP on the oxidation of malate by coupled and uncoupled mitochondria prepared from etiolated hypocotyls of mung bean were studied. In coupled mitochondria, ATP (1 mM) increased pyruvate production and decreased oxaloacetate formation without altering the rate of O2 consumption. ATP also significantly decreased oxaloacetate production and increased pyruvate production in mitochondria that were uncoupled by carbonyl cyanide p-trifluoromethoxyphenyl hydrazone plus oligomycin. In coupled mitochondria, ADP (1 mM) increased the production of both pyruvate and oxaloacetate concomitantly with the acceleration of O2 uptake to the state 3 rate. The effects of ADP were largely eliminated in uncoupled mitochondria. Whereas the ADP stimulation of oxaloacetate and pyruvate production in the coupled mitochondria is brought about primarily as the result of the accelerated rates of electron transport and NADH oxidation by the respiratory chain in state 3, ATP has significant regulatory effects independent of those that might by exerted by control of electron transport.