Characterization and partial purification of the plasminogen activator from human neuroblastoma cell line, SK-N-SH. A comparison with human urokinase.

The plasminogen activator liberated by cells of human neuroblastoma strain SK-N-SH was purified up to 400-fold, with a 40% recovery of activity, by a relatively simple procedure. This involved (NH4)2SO4 precipitation, followed by chromatography on both Affi-Gel Blue and p-aminobenzaminidine-Sepharose. The SK-N-SH activator was shown to differ from human urokinase with respect to immunological specificity, the molecular weights and isoelectric points of their enzymatically active species, the ability to be activated by fibrin and their relative sensitivities to inactivation by diisopropyl fluorophosphate. The average molecular weights of the enzymatically active species derived from strain SK-N-SH were shown to be 66,500, 64,500, 60,500 and 37,500. In the presence of fibrin, the SK-N-SH plasminogen activator appeared to be stimulated approximately 16-fold, with no apparent stimulation of urokinase activity. Urokinase is inactivated by diisopropyl fluorophosphate at a rate 6.4-fold faster than that of the SK-N-SH activator.