Further studies of an inactive form of a trypsin-like enzyme in rabbit testes

An inactive form of rabbit testicular trypsin-like activity was partially purified utilizing acid pH conditions for extraction, dialysis, and Sephadex gel filtration and ion-exchange chromatography. An inhibitor of the testicular trypsin-like activity was separated from the inactive form, but the latter still remained inactive until incubation with bovine pancreatic trypsin or “autoactivation” at pH 8. “Autoactivation” followed a sigmoidal time course and was not reversible. These results suggest the existence of a zymogen form of rabbit testicular trypsin-like activity.