Heat-Moisture Treatment of Cereal Starch Observed by X-ray Diffraction

Chitinases I and II were purified from the culture supernatant of Aeromonas sp. 10S-24 by ammonium sulfate precipitation, SP-Sephadex C-50 chromatography, Sephacryl S-200 gel filtration, and chromatofocusing. Both enzymes were most active at pH 4.0 and the optimum temperature for I and II were 50°C and 60°C. Chitinase I was stable at pHs between 4 and 9 and at temperatures below 50°C and chitinase II was stable at pHs between 5 and 7 and at temperatures below 45°C. The molecular weights were estimated by 8D8 polyacrylamide gel electrophoresis to be 112,000 and 115,000 for I and II respectively, while gel filtration showed the molecular weight to be 114,000 for both types of the enzyme. The pIs for I and II were 7.9 and 8.1, respectively. The activities of both enzymes were inhibited by Ag⁺ and iodoacetic acid.