Activities And Stabilities For Glucoamylase In Reverse Micelles

Reverse micelle is a novel biometric system to simulate living environment for enzymes. Reverse micelle is widely used in researches in activity and stability of enzymes. In this dissertation, on the premise that three kinds of reverse micelles were prepared, activities and stabilities for glucoamylase in these reverse micelles were studied.The concentration of surfactant, the molar ratio of water to surfactant, pH in water pool and temperature were important factors to impact activity of glucoamylase.When pH was 4.6 and reaction temperature was 60 癈,highest activity for glucoamylase could be obtained in bulk solution.In comparison with this system, activities in reverse micelles were distinct. In AOT-based reverse micelle, the optimum conditions were as followes:the concentration of AOT was 0.1 mol-dm-3;the molar ratio of water to surfactant was 40;pH in water pool was 4.4;reaction temperature was 50 C.While in Triton X-100-based reverse micelles, these conditions were as follows: the concentration of Triton X-100 was 0.2 mol-dm-3,the molar ratio of water to surfactant was 26;pH in water pool was 4.4;reaction temperature was 40 "C .As for lower activity in CTAB-based reverse micelles, activities for glucoamylase were not further elaborated.When the concentration of starch was lower, the queue for optimum activities of glucoamylase in three system was: in AOT-based reverse micelle>in bulk solution>inTriton X-100-based reverse micelle. When the concentration of starch was relative higher, this queue was: in bulk solution> in AOT-based reverse micelle> in Triton X-100-based reverse micelle.Thermostabilities for glucoamylase in AOT-based reverse micelle and in Triton X-100-based reverse micelle showed highest stability were achieved when Wo was equal to S.When incubation temperature was ranging from 40 to 50 C,stability in AOT-based reverse micelles was higher than stability in Triton X-100-based reverse micelle; stability in bulk solution was lowest. When incubation temperature was ranging from 60 to 70 "C,this order was that thermostability in AOT-based reverse micelle was higher than in bulk solution, however, stability in bulk solution was relative higher than in Triton X-100-based reverse micelle.Low amout of Ca2+ was a reagent for maintaining activity of glucoamylase. The optimum concentrations of Ca2+ in three systems were as follows: 1.26 mmol-dm"3, 0.54 mmol-dm"3, 150 mmol-dm"3 in AOT-based reverse micelle, in Triton X-100-based reverse micelle and in bulk solution, respectively.