Sucrose Accumulation in Red Beet Vacuoles by UDP Glucose-Dependent Group Translocation — Fact or Artefact?

Abstract

Beetroot vacuoles obtained by slicing or enzymic techniques incorporated UDP[¹⁴C] glucose predominantly into an ethanol insoluble product. No labelled sucrose was detected. Chromatographic separations and kinetic experiments suggested the results were due to glucan synthase II (EC 2.4.1.34). Evidence is presented that this enzyme can account for many of the features previously attributed to the proposed UDPglucose-dependent group translocation mechanism for sucrose transport into red beet vacuoles. The possible interference by glucan synthase II in experiments published previously is discussed.