Investigations into and an enzymic assay method of transglucosidase activity of commercial glucoamylase preparations

An enzymatic assay method was developed for the quantitative determination of transglucosidase activity in commercial glucoamylase preparations. The method is based on the determination of residual glucose after incubation of the glucoamylase preparation with this substrate under welldefined conditions (pH 4,2 and 30°C). Glucose determination was carried out by the glucose oxidase-peroxidase method and transglucosidase activity expressed in international enzyme activity units. The over-all time requirement of the analysis is 3 h with liquid and 26 h with powdered preparations. The variation coefficient was less than 3% in the former and 4% in the latter case. Optimum substrate concentration was found to be 8,3% w/v, higher glucose concentrations markedly inhibited the reaction at 30°C. Temperature optima were observed at 40 and 50°C, respectively, more elevated temperatures up to 60°C caused a strong decrease in activity.