Immobilization of α-amylase from mung beans (Vigna radiata) on Amberlite MB 150 and chitosan beads:: A comparative study

alpha-Amylase from mung beans (Vigna radiata) was immobilized on two different matrices, Amberlite MB 150 and chitosan beads. Maximum immobilization obtained was 72% and 69% in case of Amberlite and chitosan beads, respectively. The pH optima of soluble CL-amylase were 5.6, whereas that for immobilized amylase on chitosan and Amberlite was 7.0. Soluble amylase and Amberlite immobilized amylase showed maximum activity at 65 degrees C, whereas chitosan immobilized amylase showed maximum activity at 75 degrees C. a-Amylase immobilized on Amberlite showed apparent K-m of 2.77 mg/ml, whereas a-amylase immobilized on chitosan showed an apparent K-m of 5 mg/ml. The Amberlite-amylase and chitosan-amylase showed a residual activity of 43% and 27%, respectively, after 10 uses. The loss of activity for free amylase after 100 days of storage at 4 degrees C was 70%, whereas that for Amberlite- and chitosan-amylases, under the same experimental conditions, the losses were 45% and 55%, respectively. The easy availability of mung bean alpha-amylase, the ease of its immobilization on low-cost matrices and good stability upon immobilization in the present study makes it a suitable product for further use in industrial applications. (c) 2007 Elsevier B.V. All rights reserved.