Radish beta-amylase에 관한 연구

Studies on beta-Amylase of Radish

Purified preparation of beta-amylase is obtained from radish root by the means of fractional precipitation with ammonium sulfate. Purified preparation saccharifies the starch, beta-maltose being formed. Dextrinization in the true sense does not take place. Hydrolysis ceases when approximately 50% of the theoretical yield of maltose is obtained and there remains a substance (to be beta-limit dextrin) which gives a blue-violet with iodine, no glucose being formed. Stability of preparation is optimal at pH 4~9 and more completely inactivated at 65o in fifteen minutes. beta-Amylase of radish exhibits optimal activity at and near pH 5.0, which varied depending upon the buffer. Calcium and chloride ions do not effect the activities of enzyme. The results of experiments with oxidizing, alkylating and mercaptide-forming reagants which have been reported to be specific for sulfhydryl groups confirm that free sulfhydryl groups are essential to the activity of beta-amylase from radish.