Purification and characterization of a thiol‐protease from Bacteroides gingivalis strain 381

A protease from the culture supernatant of Bacteroides gingivalis 381, which hydrolyzes the chromogenic substrate Na-benzoyl-DL-arginine-p-nitroanilide (BAPNA), was partially purified by ammonium sulfate precipitation, gel filtration, and anion exchange chromatography. The molecular weight of this protease was determined by SDS-PAGE to be ca. 49,000. The optimum pH was around 7.6. The protease was stable at neutral pH and up to 40 degrees C. The isoelectric point was 4.9. The enzyme activity was enhanced by dithiothreitol, L-cysteine, and 2-mercaptoethanol and inhibited by p-chloromercuribenzoic acid, N-ethylmaleimide, and iodoacetic acid.