Sucrose-cleaving enzyme that provides UDP-glucose and fructose for various metabolic pathways. Most active in the sink tissues where it is responsible for the breakdown of the arriving sucrose. an NDP-alpha-D-glucose + D-fructose = a ribonucleoside 5'-diphosphate + H(+) + sucrose Belongs to the glycosyltransferase 1 family. Plant sucrose synthase subfamily.