京尼平交联磁性壳聚糖微球的制备及其脂肪酶的固定化

采用反相悬浮法与溶胶凝胶法结合制备磁性壳聚糖微球，并以此为载体，京尼平为交联剂，脂肪酶为模型酶进行固定化，研究了酶固定化的最优条件和固定化酶的性质。结果表明，在京尼平浓度为0.6 g/L、交联温度为55 ℃、交联时间8 h，固定化酶的比活力最大，为4.31 U/g。固定化酶在25~35 ℃，pH值在8.0有最大活性，其米氏常数Km为0.26 mol/L。同时，固定化酶具有良好的热稳定性及pH稳定性，可重复利用，且能进行磁分离。

Preparation of Genipin Cross-linked Magnetic Chitosan Microsphere and Its Immobilization on Lipase

Inverse suspension combined with the sol-gel method was deployed to prepare a magnetic chitosan microspheres. The lipase was immobilized on magnetic chitosan microspheres with genipin as the cross-linking reagent. The optimum conditions and properties of immobilization enzyme were investigated. The maximal specific activity of 4.31 U/g was achieved when the crosslinking reaction was carried out at 55 ℃ for 8 h using 0.6 g/L genipin. The optimum pH, temperature and Km of the immobilized enzyme were 8, 25~35 ℃ and 0.26 mol/L, respectively. The immobilized lipase showed improved thermal stability and remained active in a broader pH range, compared with those of free lipase. Such immobilized lipase can be recycled via the magnetic separation for a certain extent.