Localization of glycosidases in the wall of living cells from cultured Convolvulus arvensis tissue

Nine glycosidase activities were detected in isolated cell walls of cultured Convolvulus arvensis L. cells. Seven were also found in the cytoplasmic fraction. Optimal pH values were all in the acid region. The in vivo localization of some of these glycosidases was studied by assaying whole cells. Suspended cells hydrolysed the externally supplied substrates for -galactosidase (EC 3.2.1.22), -galactosidase (EC 3.2.1.23), -glucosidase (EC 3.2.1.21), -mannosidase (EC 3.2.1.24) and -xylosidase (EC 3.2.1.37). Since intracellular enzymes were latent or showed little leakage, the cells were regarded to be relatively intact. In the cases investigated, the apparent glycosidase activity values of whole cells corresponded to those of isolated cell walls. The pH-activity profiles were similar. The K_m values were identical indicating equal accessibility to substrate. The enzymes could be partially removed from the cells by strong salt solutions. The data are consistent with an in vivo cell wall localization of a number of glycosidases.Abbreviation PNP p-nitrophenyl