Abstract
Summary Inside-out plasma membrane vesicles were obtained after partition of the freeze/thawed right-side out vesicles from cucumber roots in a two phase system. A sidedness of the plasma membrane vesicles was determined by the latency of vanadate-sensitive ATPase and trypsin digestion of the enzyme. In experiments with ferricyanide-loaded vesicles a low transplasma membrane electron transport with NADH as an electron donor was generated. However, introduction of Triton X-100 into the reaction medium increased the rate of NADH oxidation several times. During incubation with ATP of both unloaded vesicles and vesicles loaded with ferricyanide, the decrease in acridine orange absorbance was observed. DCCD and sodium orthovanadate added to the reaction mixture diminished distinctly the changes of acridine absorbance. These results indicate that in vesicles the ATP-dependent H + pump is active. Incubation of the ferricyanide-loaded vesicles with NADH caused a small increase of acridine absorbance that was deteriorated in the presence of quinacrine. The contribution of the plasma membrane NADH-ferricyanide oxidoreductase in the H + transport is discussed.
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