Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitochondrial preparations isolated from rat ventral prostate were capable of oxidizing isocitrate by way of NADP isocitrate dehydrogenase (NADP-IDH) and NAD-IDH. NAD-IDH activity required ADP for activation. The pH responses for NAD-IDH and NADP-IDH were quite different. The results indicated that two different enzymes were involved in the NAD- and NADP-IDH activities. Indirect evidence indicated that NADPH-NAD transhydrogenase activity might also be involved in the mitochondrial pathway for isocitrate oxidation. NADP-IDH activity was significantly greater than NAD-IDH activity. The oxidation of isocitrate through IDH activity was coupled to the cytochrome system by NADPH- and NADH-cytochrome c reductase activities. Citrate, via isocitrate, oxidation proceeded at a much slower rate suggesting that aconitase activity could be limiting in the oxidation of citrate. In comparison to other tissues, the prostate oxidative enzyme activities are considerably lower. The results suggest that the accumulation of high prostate citrate levels is not due to a limitation imposed by a lack of IDH activity in prostate mitochondria.
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PMID:Mitochondrial isocitrate dehydrogenase and isocitrate oxidation of rat ventral prostate. 1 37

The oxidation isotherms for citrate and isocitrate by potato (Solanum tuberosum var. Russet Burbank) mitochondria in the presence of NAD differ markedly. Citrate oxidation shows positively cooperative kinetics with a sigmoid isotherm, whereas isocitrate oxidation shows Michaelis-Menten kinetics at concentrations up to 3 millimolar, and cooperative kinetics thereafter up to 30 millimolar. In the absence of exogenous NAD, the isocitrate isotherm is sigmoid throughout. The dual isotherm for isocitrate oxidation in the presence of exogenous NAD reflects the operation of two forms of isocitrate dehydrogenase, one in the matrix and one associated with the inner mitochondrial membrane. Whereas in intact mitochondria the activity of the membrane-bound enzyme is insensitive to rotenone, and to butylmalonate, an inhibitor of organic acid transport, isocitrate oxidation by the soluble matrix enzyme is inhibited by both. The membrane-bound isocitrate dehydrogenase does not operate through the NADH dehydrogenase on the outer face of the inner mitochondrial membrane, and is thus considered to face inward. The regulatory potential of isocitrate dehydrogenase in potato mitochondria may be realized by the apportionment of the enzyme between its soluble and bound forms.
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PMID:Membrane-Associated NAD-Dependent Isocitrate Dehydrogenase in Potato Mitochondria. 1666 45