Partial Purification and Properties of Sucrose-phosphate Synthase from Morning-glory Callus Cells

Abstract

Sucrose-phosphate synthase was purified 13-fold from morning-glory callus cells. The molecular weight of the enzyme was estimated to be 3 .8×10⁵ by gel filtration. The optimum pH of the enzyme was 6.5. The enzyme had the optimum temperature around 45°C . EDTA slightly inhibited the enzyme activity . UTP and UDP inhibited it strongly. Ten mMMgC1₂ or 10 mM MnC1₂ activated the enzyme activity twice as much as control. Similarly, citrate at 40 mM activated it by 40%. Other inorganic salts and metabolic intermediates did not influence the enzyme activity. The K_m values for F-6-P and UDPG were 1 .3 and 2.1 mM, respectively. Based on these data, regulation of sucrose biosynthesis at a cellular level of morning-glory callus was discussed.