Immobilization of Pseudomonas stutzeri LC2-8 lipase by a comblike and hydrophilic support with epoxy groups

A comblike and hydrophilic support with epoxy groups (PS-acyl-P(AM-co-GMA)) was synthesized by transfer radical polymerization (ATRP) method with hydrophilic acrylamide (AM) and glycidyl methacrylate as monomers, CuCl and 2-2'-bipyridine (Bipy) complex as catalyst. The oxirane content and hydrophilicity of the prepared support could be controlled via changing the monomer's mass ratio of GMA to AM. The Pseudomonas stutzeri LC2-8 lipase was immobilized by the support and the main factors influencing the immobilization process and the properties of the prepared immobilized lipase were also studied. The results show that, with n(AM):n(GMA)=20:60, immobilizing time of 24 h, coupling temperature of 30°C and pH of 7.0, the activity of the prepared immobilized lipase can achieve its maximum value of 24.1 U·g ^-1. It was found that the optimal pH and temperature for the preparation of immobilized lipase are 8.0 and 30°C, respectively. The experimental results show that the thermal stability of the immobilized lipase was improved in comparison with the free lipase. The immobilized lipase could retain above 80% of its activity after 8 consecutive operations. The results indicate that the support PS-acyl-P(AM-co-GMA) synthesized by ATRP method can be successfully used for the immobilization of the lipase and improve the stability and usefulness of the lipase effectively.