A simple assay method for α-amylase using microplates

A novel method for measuring alpha-amylase-activity was developed in this study. By adding an authentic alpha-amylase solution to a mixture of agar and gelatinized rice starch, which was fixed in a well of a microplate, the gel turbidity measured at 655 nm was decreased by the alpha-amylase action on the gelatinized starch. The intensity of the alpha-amylase-activity was in proportion logarithmically to the turbidity decrease detected by a microplate-reader. From reasonable values of standard deviation and coefficient of variation (3.7 similar to 8.9%) of the obtained data, this method makes it possible to measure alpha-amylase-activity conveniently.