modSP undergoes autoproteolysis independently during preparation. Rapid purification of modSP, to isolate the zymogen only form, becomes active when incubated with PGRP-SA, GNBP1 or GNBP3 and insoluble Lys-Pg from Staphylococcus aureus, soluble DAP-PG from Escherichia coli or curdlan. nec inhibits autoproteolysis of modSP.

Interaction in vitro; enzyme produced as a recombinant fusion protein in baculovirus and insect cell system.