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

Abstract

We have studied the effects of ATP and ADP on the oxidation of malate by coupled and uncoupled mitochondria prepared from etiolated hypocotyls of mung bean ( Vigna radiata L.).In coupled mitochondria, ATP (1 millimolar) increased pyruvate production and decreased oxaloacetate formation without altering the rate of oxygen 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 (I millimolar) increased the production of both pyruvate and oxaloacetate concomitantly with the acceleration of oxygen dptake to the state 3 rate. The effects of ADP were largely eliminated in uncoupled mitochondria. These results indicate that, 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 be exerted by control of electron transport.

The Complementary Roles of Chloroplast Cyclic Electron Transport and Mitochondrial Alternative Oxidase to Ensure Photosynthetic Performance

“…In A. thaliana , mMDH1 activity (either malate oxidation or OAA reduction) is inhibited by an increase in the ATP/ADP ratio ( Yoshida and Hisabori, 2016b ). This result is consistent with earlier studies in mung bean ( Asahi and Nishimura, 1973 ; Tobin and Givan, 1984 ). Hence, a high matrix ATP/ADP ratio could compromise the cell’s ability to manage the redox state of different NAD(P)H pools.…”

Succinate-driven reverse electron transport in the respiratory chain of plant mitochondria. The effects of rotenone and adenylates in relation to malate and oxaloacetate metabolism

“…uncoupler, this OAA was not eliminated on addition of succinate. This effect of ADP observed with uncoupled mitochondria should be ascribed to the direct regulation of the mitochondrial malate dehydrogenase by the matrix ADP/ATP ratio, which has been demonstrated with plant mitochondria [12,30,31].…”

“…On the other hand, ATP also tightly controls the production of OAA from the malate arising from succinate oxidation. It has been previously established that the plant mitochondrial malate dehydrogenase is inhibited by ATP competitively with NADI [31]. These three interfering mechanisms accounting for the dependence on ATP of the reverse electron transport, i.e.…”

The respiratory source of CO2

“…Allosteric efiects of adenylates are particularly important in glycolysis: for example, ATP-PFK is inhibited by adenylates, including ATP, and pyruvate kinase by ATP specifically; glucose-6phosphate dehydrogenase, the first enzyme specific to the PPP, is also inhibited by ATP (Pradet & Raymond, 1983;Turner & Turner, 1980). Adenylates can also control some mitochondrial enzymes, including pyruvate and malate dehydrogenases (Tobin & Givan, 1984;Wiskich, 1980) but the overall activity of the Krebs cycle is rather insensitive to the ATP/ADP ratio (Dry & Wiskich, 1982;Moller & Palmer, 1984), which (along with other evidence) suggests that the Krebs cycle will operate in illuminated green cells (Graham, 1980;Singh & Naik, 1984). NADPH (alternatively, a high NADPH/NADP ratio) inhibits glucose-6-phosphate dehydrogenase, and NADH/NAD appears to be a major regulator of Krebs cycle activity by its control of the dehydrogenases (Moller & Palmer, 1984;Wiskich, 1980).…”