Conjugation of α-amylase with dextran for enhanced stability: Process details, kinetics and structural analysis

The influence of enzyme polysaccharide interaction on enzyme stability and activity was elucidated by covalently binding dextran to a model enzyme. alpha-amylase. The conjugation process was optimized with respect to concentration of oxidizing agent, pH of enzyme solution, ratio of dextran to enzyme concentration, temperature and time of conjugate formation. and was found to affect the stability of alpha-amylase. alpha-Amylase conjugated under optimized conditions showed 5% loss of activity but with enhanced thermal and pH stability. Lower inactivation rate constant of conjugated alpha-amylase within the temperature range of 60-80 degrees C implied its better stability. Activation energy for denaturation of alpha-amylase increased by 8.81 kJ/mol on conjugation with dextran. Analysis of secondary structure of alpha-amylase after covalent binding with dextran showed helix to turn conversion without loss of functional properties of alpha-amylase. Covalent bonding was found to be mandatory for the formation of conjugate. (C) 2012 Elsevier Ltd. All rights reserved.