An alkaline protease inhibitor from Aspergillus oryzae W-1

Abstract

An alkaline protease inhibitor (API) from Aspergillus oryzae W-1 was purified to homogeneity by DEAE-Cellulose and Hydroxyl apatite column chromatographies. The molecular mass of the inhibitor was estimated to be 14KDa by SDS-PAGE and 12.5KDa by gel filtration on Sephadex G-50 column chromatography; the isoelectric point was 4.6. API was extremely heat stable and retained 100% of its original activity even after heating in a boiling water bath for 5min in the pH range of 4-6. API exhibited an inhibitory activity against the proteolytic activity of alkaline protease from A. oryzae or A. oryzae W-1, but not for subtilisin, subtilisin BPN', papain, ficin, bromelain, trypsin and α-chymotrypsin. It was found that the inhibitor was inactivated by the action of the latter seven enzymes.