Immobilization of α-amylase on gum acacia stabilized magnetite nanoparticles, an easily recoverable and reusable support

In this work, alpha-amylase is immobilized, using glutaraldehyde, onto magnetite nanoparticles prepared using gum acacia as the steric stabilizer (GA-MN), for the first time. The immobilization of amylase to GA-MN is very fast and the synthesis of GA-MN is very simple. The use of GA enables higher immobilization of alpha-amylase (60%), in contrast to the unmodified magnetite nanoparticles (similar to 20%). The optimum pH and temperature for maximum enzyme activity for the immobilized amylase are identified to be 7.0 and 40 degrees C, respectively, for the hydrolysis of starch. The kinetic studies confirm the Michaelis-Menten behavior and suggests overall enhancement in the performance of the immobilized enzyme with reference to the free enzyme. Similarly the thermal stability of the enzyme is found to increase after the immobilization. The GA-MN bound amylase has also been demonstrated to be capable of being reused for at least six cycles while retaining similar to 70% of the initial activity. By using a magnetically active support, quick separation of amylase from reaction mixture is enabled. The catalytic rate of amylase is actually found to enhance by twofold after the immobilization, which is extremely advantageous in industry. At higher temperature, the immobilized enzyme exhibits higher enzyme activity than that of the free enzyme. (C) 2013 Elsevier B.V. All rights reserved.