Comparison of the Kinetic Behavior toward Pyridine Nucleotides of NAD-Linked Dehydrogenases from Plant Mitochondria.
In this article we compare the kinetic behavior toward pyridine nucleotides (NAD(+), NADH) of NAD(+)-malic enzyme, pyruvate dehydrogenase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, and glycine decarboxylase extracted from pea (Pisum sativum) leaf and potato (Solanum tuberosum) tuber mitochondria. NADH competitively inhibited all the studied dehydrogenases when NAD(+) was the varied substrate. However, the NAD(+)-linked malic enzyme exhibited the weakest affinity for NAD(+) and the lowest sensitivity for NADH. It is suggested that NAD(+)-linked malic enzyme, when fully activated, is able to raise the matricial NADH level up to the required concentration to fully engage the rotenone-resistant internal NADH-dehydrogenase, whose affinity for NADH is weaker than complex I.
Pascal
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Laboratoire de Physiologie Cellulaire Vegetale, Centre d'Etudes Nucléaires de Grenoble et Université Joseph Fourier, 85X, F-38041 Grenoble-Cedex, France.
Dumas
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Douce
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