Purifications and Some Properties of Two Chitinases fromStreptomyces orientalisWhich LyseRhizopusCell Wall

Streptomyces orientalis was selected as a microorganism which produced chitinase having lytic activity on Rhizopus cell wall. Two chitinases (chitinase I and II) which had very similar properties were purified to an ultracentrifugally homogeneous state from the culture broth of this organism by SP-Sephadex and Sephadex G–100 chromatographies. Molecular weights of chitinase I and II were estimated as about 33,000 and 25,000, and isoelectric points as pH 8.80 and 8.65, respectively. Both chitinases were most active at pH values between 5.5 and 6.5, and were stable in the range of pH 6.0 to 8.0 at 40°C for 3 hr. They were stable at temperatures below 50°C for 15 min. Rhizopus cell wall was almost completely degraded by a cooperative action of these chitinases, and a protease and a chitosanase from Bacillus R–4.