Extraction and purification of beta-amylase from stems of Abrus precatorius by three phase partitioning

The stems of Abrus precatorius were used to extract a beta-amylase enriched fraction. A three phase partitioning method and a Doehlert design with 3 variables (ratio of crude extract/t-butanol, the ammonium sulphate saturation and pH) were used. The data was fitted in a second-order polynomial model and the parameters were optimized to enrich beta-amylase. Experimental responses for the modulation were recovery of activity and the purification factor. The optimal conditions were: a ratio of crude extract/t-butanol of 0.87 (v/v), saturation in ammonium sulphate of 49.46% (w/v) and a pH of 5.2. An activity recovery of 156.2% and a purification factor of 10.17 were found. The enriched enzyme was identified as a beta-amylase and its molecular weight was 60.1 kDa. Km and Vmax values were 79.37 mg/ml and 5.13 U/ml, respectively and the highest activity was registered at a temperature of 70 °C and a pH between 6 and 6.5. A significant stabilization of the beta-amylase was observed up to 65 °C.