Activation of poly(dimer acid-co-alkyl polyamine) particles for covalent immobilization of α-amylase

Poly(dimer acid-co-alkyl polyamine) particles were activated by using various chemicals such as carbodiimide (CDI), ethylene diamine (EDA), and hexamethylene diamine (HMDA) and studied as support materials for covalent immobilization of α-amylase. The activities of the immobilized enzymes on these activated particles were investigated. The highest activity of free enzyme was obtained at pH 7.5 while this value was shifted to pH 6.5 for CDI and EDA activated systems and to pH 8.0 for HMDA activated system. The highest activities of immobilized enzymes were obtained at higher temperature (55 °C) than that of the free enzyme (40 °C). Kinetic parameters were calculated as 2.51, 3.13, 3.47 and 3.17 g dm−3 for Km and 1.67 × 10−3, 6.16 × 10−4, 7.34 × 10−4 and 3.30 × 10−4 g dm−3 min−1 for Vmax for the free enzyme, and CDI, EDA and HMDA activated immobilized systems, respectively. Enzyme activities were found to be about 75.0%, 62.5% and 95.0% of the original, for CDI, EDA and HMDA activated systems, respectively, after one month of storage while free enzyme lost its activity completely in 20 days. In repeated batch experiments, after 40 uses in 3 days; 91.3%, 77.6% and 99.1% of the original enzyme activities were retained by CDI, EDA and HMDA activated systems, respectively. Among the systems prepared, HMDA activated poly(dimer acid-co-alkyl polyamine) particles demonstrated the highest stability and efficient reusability for the immobilized α-amylase.