Impact of ionic liquid physical properties on lipase activity and stability
Impact of ionic liquid physical properties on lipase activity and stability
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DOI：
10.1021/ja028557x
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发表时间：
2003-04-09
影响因子：
15
通讯作者：
Russell, AJ
中科院分区：
文献类型：
--
作者：
Kaar, JL;Jesionowski, AM;Russell, AJ
研究了含六氟磷酸盐、乙酸酯、硝酸盐、甲烷磺酸盐、三氟乙酸酯和三氟甲磺酸等阴离子的二烷基咪唑和吡咯烷基离子液体中脂肪酶的活性和稳定性。考察了在这些离子液体和几种有机溶剂中脂肪酶催化甲基丙烯酸甲酯酯交换反应的初始速率，以及己二酸二乙烯酯和1，4-丁二醇酯的多酯交换反应。游离脂肪酶(Candida Rugosa)催化甲基丙烯酸甲酯在1-丁基-3-甲基咪唑六氟磷酸盐中的酯交换反应速率是正己烷中的1.5倍。然而，在所研究的所有“亲水性”离子液体中都没有观察到可检测到的活性。采用吸附、聚乙二醇改性、聚氨酯泡沫塑料固定化等稳定酶的方法均不能有效提高亲水性离子液体的酶活性。使用Novozym 435在1-丁基-3-甲基咪唑六氟磷酸盐中进行的聚酯交换反应，由于聚合物的沉淀，得到了重平均分子量限制在2900 Da的聚酯。溶致变色研究和分配系数测量表明，离子液体比正己烷、乙腈和四氢呋喃等有机溶剂更具极性和亲水性。稳定性研究表明，脂肪酶在离子液体中表现出比在有机溶剂(包括正己烷)中更大的稳定性。
Lipase activity and stability was investigated in dialkylimidazolium and pyrrolidinium-based ionic liquids with a variety of anions including hexafluorophosphate, acetate, nitrate, methanesulfonate, trifluoroacetate, and trifluoromethylsulfonate. The initial rate of lipase-catalyzed transesterification of methyl methacrylate in these ionic liquids and several organic solvents was examined as well as the polytransesterification of divinyl adipate and 1,4-butanediol. Free lipase (Candida rugosa) catalyzed the transesterification of methyl methacrylate in 1-butyl-3-methylimidazolium hexafluorophosphate at a rate 1.5 times greater than in hexane. However, no detectable activity was observed in all the "hydrophilic" ionic liquids studied. Methods of enzyme stabilization including adsorption, PEG-modification, and immobilization in polyurethane foam were ineffective in improving enzymatic activity in the hydrophilic ionic liquids. Polytransesterifications performed in 1-butyl-3-methylimidazolium hexafluorophosphate using Novozym 435 produced polyesters with weight average molecular weights limited to 2900 Da due to precipitation of the polymer. Solvatochromic studies and partition coefficient measurements suggest that ionic liquids are more polar and hydrophilic than organic solvents such as hexane, acetonitrile, and tetrahydrofuran. Stability studies indicate that lipases exhibit greater stability in ionic liquids than in organic solvents including hexane.