Preparation and Characterization of Amino-Functionalized Zeolite/SiO2 Materials for Trypsin-Chymotrypsin Co-immobilization

摘要

Inorganic supports have attracted increased attention in enzyme immobilization since they not only improve enzyme stability but also reduce the final cost of enzymatic reactions. Herein, we explored the suitability of the amino-functionalized zeolite/SiO2 materials to co-immobilize trypsin-chymotrypsin mixture. For this purpose, the trypsin-chymotrypsin mixture was co-immobilized on the amino-functionalized zeolite/SiO2 materials and the immobilization yield was 80.7 +/- 7.6%. The pre-support and its modification were characterized by several techniques. Besides, the charges of the materials were investigated by zeta potentials at pH 5.0. As expected, the zeta potentials shifted from - 24.4 to - 8.16 mV after amino functionalization. Following immobilization, whereas the optimum pH (9.0) was not changed, the optimum temperature shifted from 50 to 40 degrees C. On the other hand, the immobilized trypsin-chymotrypsin showed comparatively higher thermal stability and storage stability than the soluble trypsin-chymotrypsin. The kinetic parameters were also calculated, however, while no significant change was observed in V-max, K-m value increased, which means that the affinity of enzyme to the substrate decreased after immobilization. Most strikingly, the residual activity of immobilized trypsin-chymotrypsin was 58% after eight repeated cycles. In conclusion, the preliminary experiments inferred that the amino-functionalized zeolite/SiO2 particles can be suitable and helpful support for trypsin-chymotrypsin immobilization. Graphic