Immobilization of trypsin on porous glycidyl methacrylate beads: effects of polymer hydrophilization.

The immobilization of trypsin at porous glycidyl methacrylate (GMA-GDMA) beads was investigated. In particular, the effects of surface modification of the beads through hydrophilic polymers on the amount protein immobilized and on the extent of retained activity after immobilization were adressed. Furthermore, immobilization at unmodified and hydrophilized beads from aqueous solution was compared to that from a water-in-oil microemulsion. It was found that the amount trypsin immobilized at the unmodified GMA-GDMA beads was significantly higher than that at hydrophilized GMA-GDMA beads. However, also the extent of specific activity loss after immobilization was larger for the unmodified than for the hydrophilized beads. Despite the latter, however, the total activity displayed by the hydrophilized beads was comparable to the unmodified beads at best. On the other hand, by peforming the immobilization from the microemulsion a high immobilization yield can be reached even for the hydrophilized beads, which also results in a higher degree of retained activity in the latter case than obtained for immobilization at the unmodified beads. Using this approach therefore resulted in the highest total activity of the trypsin-activated GMA-GDMA beads.