磁性聚乙烯醇缩丁醛微球固定化α-淀粉酶

Immobilization of α-Amylase on Magnetic Polyvinylbutyral Microspheres

制备出磁性聚乙烯醇缩丁醛微球,并用该微球做载体,采用共价交联法固定α 淀粉酶。最佳固定化工艺条件为:pH=6 07,激活和交联时戊二醛的质量分数分别为4%和0 025%。在最佳固定化条件下所制磁性固定化酶的活力为25426 3U/g微球,蛋白载量为187 2mg/g微球,比活为135 8U/mg蛋白,活性回收率为36 9%。磁性固定化酶的理化性质为:磁性固定化酶的最适温度(60℃)比自由酶(50℃)高,最适pH(6 97)与自由酶相同,磁性固定化酶Km(米氏常数)值(5 7×10-4kg/L)较自由酶Km值(5 0×10-4kg/L)大,热稳定性、pH稳定性及操作稳定性均比自由酶有所提高。

Magnetic polyvinylbutryal microspheres were prepared and used as carrier for immobilizing αamylase by covalently crosslinking method.The optimum conditions for immobilization were settled as follows.At pH=607,the mass fractions of glutaraldehyde for activation and crosslinking were 4% and 0025% respectively.The results showed that activity of the magnetic immobilized enzyme (MIE) was 25426 U/g carrier,the protein binding capacity was 187mg/g carrier,the specific activity was 136 U/mg protein and the activity rentention was 369%.The optimum temperature of MIE was 10 degree higher than that of natural αamylase (50 ℃).The optimum pH value of MIE (697) was the same as that of the natural enzyme.The measured Km(MichaelisMenten constant) values in MIE and natural αamylase were 57×10-4 kg/L and 50×10-4 kg/L respectively.Compared with natural enzyme,MIE has better thermal stability,pH stability,working stability and storage stability.