Sialidase activity in mouse neuroblastoma cell lines.

Sialidase activity was determined for three different neuroblastoma clonal lines derived from the A/J strain mouse C1300 neuroblastoma line. For each cell line, the endogenous and exogenous activities were less than 1 nmol sialic acid released/mg protein/90 min and 50 min reaction time, respectively. The C1300 tumor had similarly low levels of sialidase activity. The sialidase activity associated with the neuroblastomas is less than that associated with synaptosomes. Each cell line had a distinctly different ganglioside pattern varying in complexity from GM3 to GD1a. Treatment of the cells withVibrio cholerae sialidase under isosmotic conditions showed that cell-surface sialyl residues were susceptible to sialidase activity, with some of the susceptible residues coming from the ganglioside constituents. Of the total number ofV. cholerae sialidase-releasable sialyl residues, 50-60% were released by the neuroblastoma sialidase acting on endogenous substrate.