A Novel Method to Detect β-Cyclodextrin Glucosyl Transferase (β-CGTase) Activity on Polyacrylamide Gels

b-cyclodextrin glucosyl transferase (b-CGTase) hydrolyses starch to produce b-cyclodextrin by transglycosylation (cyclization) activity. The conventional method for detection of b-CGTase activity is based on detecting starch hydrolysis by iodine staining. This method reveals all amylolytic enzymes, but can not discriminate them. In the present study, we introduce a new method for specific detection of b-CGTase activity and its specific product i.e. b-cyclodextrin by polyacrylamide gel. In this method, solution containing b-CGTase is subjected to electrophoresis on 10% polyacrylamide gel. Then, the gel is covered with an indicator gel containing phenolphthalein, soluble starch, and agar. After a short incubation, sodium carbonate solution is added and the positive result is indicated by the emergence of a colorless band in the red context of the indicator gel. Since the production of b-cyclodextrin via cyclization is unique to b-CGTase, the emergence of clear bands is indicative of b-CGTase presence. However, in conventional starch-iodine method, all amylolytic enzymes including b-CGTase give positive results. Therefore, for detection of b-CGTase, the phenolphthalein indicator gel method, compared to the starch-iodine method, is more specific