木瓜蛋白酶交联聚体的制备及性质

采用交联酶聚体(CLEAs)技术制得了木瓜蛋白酶CLEAs, 优化了制备条件. 以纯乙醇为蛋白沉淀剂, 质量分数40%戊二醛为交联剂, 于4 ℃下对酶沉淀聚体交联16 h; 所得木瓜蛋白酶CLEAs的最适pH为6.0(游离酶最适pH=7.0), 最适温度范围由游离酶的80 ℃拓宽为50～80 ℃, 热稳定性和溶液稳定性亦明显提高; 微观形貌分析证明木瓜蛋白酶CLEAs优良的催化效能及稳定性来自于CLEAs单元所具有的高比表面积及单元内部多点共价固定的结合方式.

Preparation and Properties of Cross-linked Enzyme Aggregates of Papain

Cross-linked enzyme aggregates(CLEAs) is a non-carrier immobilization technique with the advantages of simple preparation, low cost and high unit activity. In this paper, papain-CLEAs were prepared and the effects of precipitation and cross-linking on CLEAs activity were investigated. It is shown that the highest activity of papain-CLEAs were obtained when using pure ethanol as precipitant, 40% glutaraldehyde as cross-linker and cross-linking at 4 ℃ for 16 h. Moreover, the optimal catalytic conditions and operational stabilities of papain-CLEAs were characterized. Papain-CLEAs shifted the optimal pH from 7.0 to 6.0 and broaden the optimal temperature to the range of 50-80 ℃. Papain-CLEAs also enhanced thermal and storage stabilities compared with free enzyme. It is indicated from the morphology that these improved performances resulted from the high surface area and multi-points covalent cross-linking structure of every single papain-CLEAs. These improved characters show practical advantages of papain-CLEAs in biocatalysis.