Accumulation of sucrose in vacuoles isolated from red beet tissue

Vacuoles were isolated from red beets (Beta vulgaris L.) by slicing the tissue and separated using a discontinuous dextran gradient centrifugation. The uptake of sucrose against a concentration gradient into the dextran-impermeable [3H]-H2O space of these organelles was studied using silicone layer filtering centrifugation on both fluorometric and 14C-measurement of sucrose. The rate is 24 nmol sucrose (unit betacyanin)-1 h-1 and appears to be stimulated by ATP to an uptake rate of 34 nmol. Control experiments with slices cut from red beet tissue and incubated with [14C]sucrose gave comparable results. An ATPase activity dependent on both Mg2+ and K+ seems to be localized at the inner surface of the tonoplast. This activity is strongly inhibited by EDAC and tartrate and there is no effect of oligomycin, whereas a slight stimulation was caused by DCCD.