Abstract
A strain of Serratia, isolated from an intestinal canal of a silkworm, produced a large quantity of protease. The enzyme was extracellular and was named Serratiopeptidase, tentatively. Protease production of this strain was over 3 times as much as that of Serratia marcescens which was known as a protease-producing organism. The highly purified enzyme was prepared from the culture supernatant through ammonium sulfate precipitation, acetone fractionation, DEAE-cellulose column chromatography and gel filtration on Sephadex G-75.
The purified enzyme moved homogeneously with a sedimentation constant, s20, w of 3.8S in ultracentrifugation and the molecular weight was determined to be 6.0×104 by the Archibald method. Determination of the ultraviolet absorption spectrum indicated the E1%280mμ, 1cm was 13.0. Neither carbohydrate nor sulfur-containing amino acid was detected in the purified enzyme preparation.
The enzyme showed maximal activity at pH 9.0 and at 40°C, and was stable under lower temperatures over the pH range from 5 to 10, whereas it was unstable at 37°C in alkaline conditions. The enzyme was completely inactivated by heating at 55°C for 15 min.
