The present study compares the exogenous NAD(P)H oxidation and the membrane potential (A$) generated in mitochondria isolated from different tissues of an important agricultural crop, sugar beet (Beta vulgaris). We observed that mitochondria from taproots, cold-stored taproots, and in vitro-grown tissue cultures contain a functional NADH dehydrogenase, whereas only those isolated from tissue cultures displayed a functional NAD(P)H dehydrogenase. It is interesting that the NADH-dependent A$ of mitochondria from cold-stored taproots and from tissue cultures was not affected by free Caz+ ions, whereas free CaZ+ was required for the mitochondrial NADPH oxidation by in vitro-grown cells and cytosolic NADH oxidation by mitochondria from fresh taproots. A tentative model accounting for the different response to Caz+ ions of the NADH dehydrogenase in mitochondria from cold-stored taproots and tissue cultures of B. vulgaris is discussed.
OXIDATION OF EXTERNAL NAD(P)H BY MITOCHONDRIA FROM TAPROOTS AND TISSUE-CULTURES OF SUGAR-BEET (BETA-VULGARIS)
ZOTTINI, MICHELA;
1993
Abstract
The present study compares the exogenous NAD(P)H oxidation and the membrane potential (A$) generated in mitochondria isolated from different tissues of an important agricultural crop, sugar beet (Beta vulgaris). We observed that mitochondria from taproots, cold-stored taproots, and in vitro-grown tissue cultures contain a functional NADH dehydrogenase, whereas only those isolated from tissue cultures displayed a functional NAD(P)H dehydrogenase. It is interesting that the NADH-dependent A$ of mitochondria from cold-stored taproots and from tissue cultures was not affected by free Caz+ ions, whereas free CaZ+ was required for the mitochondrial NADPH oxidation by in vitro-grown cells and cytosolic NADH oxidation by mitochondria from fresh taproots. A tentative model accounting for the different response to Caz+ ions of the NADH dehydrogenase in mitochondria from cold-stored taproots and tissue cultures of B. vulgaris is discussed.Pubblicazioni consigliate
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