Leakage and storage of sucrose during sucrose synthesis in the corn scutellum

Abstract

During incubation of corn scutellum slices in fructose solutions (0·1–0·9 M) sucrose leaked ( leakage A) from the slices, and additional leakage ( leakage B) occurred upon dilution of the fructose solution to 0·1 M or less. Sucrose was also stored within the slices, and net sucrose synthesis (stored plus leaked) was 20–25 μmoles/hrg fresh wt. Fructose concentration of the bathing solution had little effect on net sucrose synthesis or on the amount of sucrose leakage A. However, with increased fructose concentration, the amount of sucrose stored decreased while the amount of sucrose leakage B increased. The rate of sucrose leakage B was strongly inhibited by fructose, galactose, polyhydric alcohols and 2,4-dinitrophenol. After incubation of the slices in 14C-fructose, leakage A and leakage B sucrose were found to be quite different with respect to specific activity and distribution of 14C between the fructose and glucose moieties. From these results and the results of inhibition studies, it is concluded that the two types of leakage have different origins within the cell.