Naphthylamidase (arylaminopeptidase) activities in rat cartilages and bone

Extracts of epiphyseal articular and costal cartilages and of metaphyseal bone showed different profiles of activity against 21 aminoacyl beta-naphthylamides. Except for the activity against arginyl and lysyl beta-naphthylamides, most of the activities required the presence of Triton X-100 for extraction, suggesting that in situ, the enzymes are bound to or within membranous structures. Histochemical studies demonstrated that most, if not all, activity was intracellular. The activity is enhanced by Co2+. TAME (2 X 10(-4) mol/l) inhibits activity against leucyl beta-naphthylamide and some others, but has little, if any, inhibition of activity against alanyl beta-naphthylamide. Gel filtration of the extract showed a high molecular weight active fraction eluting with proteoglycan, and an active fraction with an approximate molecular weight of about 230,000. Two active fractions are obtained by gradient elution from DEAE-cellulose.