有机相温敏性脂肪酶催化剂的结构和催化特性

Structural and catalytic characteristics of temperature-responsive lipase catalyst in organic solvents

采用不同链长PEO嵌段的Pluronic分子P123、P105、F127及F108，将其端羟基氧化为醛基，使其与脂肪酶CALB的氨基反应形成纳米结合物。TEM分析结果显示CALB-Pluronic结合物在甲苯中呈现直径为20～40 nm的纳米颗粒。所形成的CALB-Pluronic结合物在4-甲基-2-戊酮中呈现温度响应性，降低温度可使酶催化剂沉淀出来，结合物中的Pluronic高分子PEO嵌段越长，其最低临界共溶温度（LCST）越高。采用甲苯为溶剂、正丁醇及正己酸为底物，37℃下的催化实验结果显示 CALB-Pluronic 纳米结合物比天然 CALB 的表观活性提高4～6倍，而反应结束后可通过降温回收酶催化剂，显示出脂肪酶-Pluronic纳米结合物在有机相酶催化中的良好应用前景。

Pluronic polymers P123, P105, F127 and F108, which have different chain lengths of PEO block were modified to generate aldehyde terminals for the conjugation with surface amine groups of CALB. The resulted Pluronic-CALB conjugates were characterized by SDS-PAGE and transmission electron microscopy. It was showed that the conjugates were dispersed well in toluene and appeared as nanoparticles with diameters ranged from 20 nm to 40 nm. The conjugates can be dispersed in methyl isobutyl ketone （MIBK） with temperature-responsive properties. The conjugate with a longer chain length of PEO block appeared a higher low critical solution temperature （LCST）. The apparent activity of the conjugates in toluene at 37℃ was increased by 4 to 6 folds compared to the native counterpart. The recovery of CALB conjugates can be accomplished by precipitation at low temperature, making this enzyme conjugate suitable for industrial enzymatic synthesis in organic media.