Raw Starch Digestion by α‐Amylase and Glucoamylase from Chalara paradoxa

Abstract

AbstractGlucoamylase and α‐amylase of Chalara paradoxa were separated by hydrophobic column chromatography using butyl‐Toyopearl 650M. The α‐amylase showed the highest activity at pH 5.5 and 45°C, and was stable in the pH range of 5.5–6.5 and at temperatures lower than 40°C. The glucoamylase showed the highest activity at pH 5.0 and 45°C, and was stable in the pH range of 4.0–7.5 and at temperatures lower than 45°C. The molecular mass of the α‐amylase and glucoamylase estimated by SDS polyacrylamide gel electrophoresis was 80,000 and 68,000, respectively. Both glucoamylase and α‐amylase could digest more effectively raw rice starch and raw corn starch than raw sago starch and raw potato starch. 2% raw rice starch in 10 ml solution was digested by more than 90% by 100 units of each amylase. When these amylases were used combined, raw corn starch was more effectively digested than they were used singly. This cooperative action in raw corn starch digestion was also observed when. C. paradoxa α‐amylase and R. niveus glucoamylase were combined.