Streptomyces Pepsin Inhibitor-Insensitive Carboxyl Proteinase from Lentinus edodes

Abstract

A Streptomyces-pepsin inhibitor (S-PI or Pepstatin Ac), and DAN-insensitive carboxyl proteinase was found in a still culture filtrate of Lentinus edodes. The new carboxyl proteinase was purified, and about 9 mg purified enzyme was obtained from 19 liters of culture filtrate, with 11 % recovery. The enzyme showed a single band on polyacrylamide gel electrophoresis. The molecular weight and isoelectric point were 40, 000 and pH 4.2, respectively. The enzyme did not contain histidine and was composed of 387 amino acid residues. The enzyme was most active between pH 2.72.9, and stable over a pH of 3.2-5.2 for 3 hr at 37°C. The enzyme was not inhibited by S-PI or synthetic pepsin inhibitors such as DAN and EPNP. The physicochemical and enzymological properties were very similar to those of Scytalidium lignicolum carboxyl proteinase A, which was reported to be an S-PI-, and DAN-insensitive carboxyl proteinase.