Metallic/bimetallic magnetic nanoparticle functionalization for immobilization of α-amylase for enhanced reusability...

Novel magnetic nanoparticles coated with silica and gold were synthesized for immobilization of α-amylase enzyme and characterized with Fourier transform infrared spectroscopy, transmission electron microscopy. Effect of various limiting factors such as substrate concentration, temperature, and pH on the catalytic activity of enzyme was investigated. The optimum pH for free and immobilized enzyme was found unaffected (7.0), whereas optimum temperature for the enzyme activity was increased from 60°C for free enzyme to 80°C for immobilized counterpart. The gains in catalytic attributes concomitant to ease of recovery of the enzyme reflect the potential of the approach and the product to be useful for the enzymatic bioprocessing. The Michaelis-Menten constant (Km) value of the immobilized α-amylase was higher than that of free α-amylase, whereas maximum velocity (Vmax), and turn over number (Kcat), values were almost similar. Immobilized α-amylase maintained 60% of the enzyme activity even after recycling ten times.