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