Abstract
A new raw starch-digesting amylase was obtained from a strain of mold, identified as Chalara paradoxa. This enzyme was purified by starch adsorption, DEAE-Cellulose column chromatography and Toyopearl HW-55 gel filtration to 60 fold of the activity of the original culture liquor. It gave a single band on disc gel electrophoresis, and the molecular weight estimated by SDS disc gel electrophoresis was 82, 000. In isoelectric focusing, the enzyme showed six bands, at isoelectric points (pI) of 3.20, 3.26, 3.34, 3.41, 3.49 and 3.52. This amylase showed maximum activity at 45-50°C and pH 5.0. The pH-stability range was relatively wide. The enzyme retained more than 80% of its initial activity in the range of pH 4.5 to 7.5. It was stable below 50°C, and thermostability was improved by the addition of calcium ion. The relative reaction rates of the enzyme on various metal ions and inhibitors were also studied. The anomeric configuration of the product obtained from starch by the enzyme was beta-configuration. The ratio of raw starch-digesting activity to gelatinized starch-saccharifying activity of the enzyme was 31.5%.
