Inhibition of guanidinobenzoatase by a substrate for trypsin-like enzymes.

Guanidinobenzoatase is a proteolytic enzyme capable of degrading fibronectin and is a tumour associated enzyme. Guanidinobenzoatase has been shown to be an arginine selective protease and is distinct from trypsin, plasmin and thrombin, the latter enzymes can be assayed with bis(carbobenzyloxycarbonyl-L-argininamido)-Rhodamine or BZAR. Guanidinobenzoatase is inhibited by BZAR when the enzyme is assayed in free solution and when the enzyme is cell-bound in frozen sections of tumour containing tissues. It is proposed that BZAR and its analogues may be of value in inhibiting tumour cell invasion in vivo and also that the selectivity of BZAR may be used to direct cytotoxic drugs to tumour cells possessing active guanidinobenzoatase.