Localization of donor and acceptor sites of NADH dehydrogenase activities using inside-out and right-side-out plasma membrane vesicles from plants

AbstractInside-out and right-side-out plasma membrane vesicles from sugar beet (Beta vulgaris L.) leaves, prepared by aqueous two-phase partitioning, were used to localize donor and acceptor sites and to determine substrate affinities for plasma membrane-bound NADH dehydrogenase activities. NADH-ferricyanide and NADH-cytochrome c reductase activities were approx. 30% latent with inside-out vesicles and about 80% latent with right-side-out vesicles, indicating that both donor and acceptor sites for these activities are located on the cytoplasmic surface of the plasma membrane, and that a possible transplasma membrane electron transport would constitute only a minor proportion of the total activity