Characteristics of ATPase from sugarcane protoplast and vacuole membranes

Abstract

Characteristics of membrane‐associated ATPase from commercial Hawaiian varieties of sugarcane (Saccharum spp. hybrids) were investigated in preparations from sugarcane cell suspension culture and from stalk tissues of the intact plant. In order to examine comparable preparations, protoplasts and vacuoles, in turn, were obtained from both sources. ATPase from preparations of crude protoplast membranes and tonoplast had a pH optimum of 6 to 6.5. The relative effectiveness of divalent cations in stimulating ATPase was Mg2+ > Mn2+≥ Co2+ > Ca2+≥ Zn2+. Enzyme activity was not stimulated by K+, nor by other monovalent cations. Protoplasts and vacuoles from both sources showed significant acid phosphatase activity. Acid phosphatase activity was inhibited by molybdate, but ATPase activity was unaffected. Membrane preparations from protoplasts contained inorganic pyrophosphatase, but enzyme activity was low or not present in tonoplast preparations. Cell suspension and stalk tissue preparations hydrolyzed a large number of nucleoside di‐ and triphosphates. The hydrolysis is most likely due to a series of enzymes rather than a single enzyme. ATPase from protoplast and tonoplast preparations was inhibited 30–50% by diethylstilbestrol and sodium ortho‐vanadate and was unaffected by ionophores. This study illustrates the complexity of phosphohydrolase activities in membrane preparations from sugarcane. The study, however, also illustrates substantial similarity in the behavior of these enzymes, whether they are derived from the plant itself or from cell cultures originating from comparable tissues of the plant.

The role of the vacuole in the accumulation and mobilization of sucrose

“…Vanadate, an inhibitor of plasma membrane ATPase, was without effect . ATPase activities have also been demonstrated in vacuoles from Hevea latex [10], Hippeastrum and Tulipa vacuoles [22,36] and sugarcane suspension cells [32] . Thus despite early doubts [6] there now seems good evidence that the tonoplast does possess ATPase activity .…”

Temporal and Spatial Regulation of Sucrose Accumulation in the Sugarcane Stem

“…Vacuoles isolated from sugarcane cells grown in suspension culture hydrolysed ATP (Thom et al 1983;Thom and Komor 1984a) and transported 3-OMG against a concentration gradient (Thom et al 198227). These results indicated that sugarcane has a tonoplast-bound ATPase that translocates protons into the vacuole thereby generating the ;+ H+ H+ proton gradient (Thom and Komor 1985) needed for operating a hexose H+-antiport system ([3] of Fig.…”

Electrogenic Proton Translocation by the ATPase of Sugarcane Vacuoles

“…These isolated vacuoles hydrolyze ATP (23,24) and transport sugars against a concentration gradient (22 (11), but the value is close to zero when measured as the accumulation of thiocyanate (24). Both values must be regarded with caution since it is difficult to correct for a significant amount of probe adsorption.…”