冻干壳聚糖微球固定化纤维素酶的研究

Study on Immobilized Cellulase for Dried-chitosan Beads

分别以冻干壳聚糖微球和湿壳聚糖微球为载体，戊二醛为交联剂进行纤维素酶的固定化研究，并对2种固定化酶的热稳定性、米氏常数、重复利用次数、pH值加以对比分析。确定酶固定化的适宜条件为：0．03g冻干壳聚糖微球与10mL4g/L戊二醛交联4h后，加入10mg酶固定2h，酶活力回收率为96．3％；0．1g湿壳聚糖微球与10mL 2g／L戊二醛交联2h后，加入6mg酶固定4h，酶活力回收率为62．4％。与游离酶相比，2种固定化酶的米氏常数均降低；具有很好的热稳定性；最适酶解温度分别为60℃，50℃；酶解反应适宜pH范围3．0—4．0，最适pH值均向酸性方向移动。冻干载体更易与酶分子结合，酶活力回收率高于湿载体固定化酶。

Immobilizations of cellulose on carriers of dried-ehitosan and wet-chitosan beads respectively crosslinked by glutaraldehyde were studied in this study for which thermalstability, Micbaelis constant, times of reuse and pH were analyzed respectively for comparison of the two carriers. The optimum conditions of enzyme immobilization were obtained as follows： cross-linking 0. 03 g of dried chitosan beads with 10mL of 4 g/L glutaraldehyde for 4 h, and then adding 10 mg of enzyme for 2 h of immobilization, the recovery of enzyme activity was 96. 31%. In contrast, cross-linking 0. 1 g of wet chitosan beads with 10mL of 2 g/L glutaraldehyde for 2 h, and then adding 6 mg of enzyme for 4 h of immobilization, the recovery of enzyme activity was 62.4%. Compared with free enzyme, the both immobilized enzymes had low Michaelis constants and very good values of thermalstability; the optimum enzymolysis temperatures for wet-and dried-chitosan were 60 and 50℃ respectively; the favorite pH ranged in 3.0 - 4. 0 with optimum value moving to acetic side. The dried carrier combined with enzyme molecules easier and had a higher recovery of activity than that of the wet one.