The Biosynthesis of Sucrose and Nucleoside Diphosphate Glucoses in Phaseolus aureus

Abstract

Sucrose-phosphate synthetase is detectable only in intact chloroplast preparations of Phaseolus aureus. In contrast, sucrose synthetase and uridine diphosphate glucose (UDP-glucose) pyrophosphorylase activities are low in extracts of photosynthetic tissues of P. aureus but are high in extracts of nonphotosynthetic tissues. Activities for ADP-, dTDP-, CDP-, and GDP-glucose pyrophosphorylases are generally higher in extracts of photosynthetic tissues of P. aureus than in extracts of nonphotosynthetic tissues. The high levels of sucrose synthetase and of UDP-glucose pyrophosphorylase found in dark-grown hypocotyls begin to decline about 4 hours after exposure to light at a rate of 50% every 3 hours.