Abstract:

To investigate the partition behavior of papain in the ionic liquids aqueous two-phase system containing [C_nmim]BF₄+NaH₂PO₄, the binodal curve and liquid-liquid equilibrium was measured by means of cloud point at T 298.15 K and a 3D theoretical model was established. The data fitting of binodal and the equilibrium was based on Merchuk, Othmer-Tobias and Bancroft equations with a high degree of fitting of above 0.975 and 0.994, respectively. Then, the correlation between logarithm of the partition coefficient and both the concentration of ionic liquids in upper phase and the salt concentration in lower phase was studied, and a partition model was established by Matlab. The mean relative deviations between the experimental and calculated data were <5%, which was sufficient to prove the reliability of this model.

Key words: papain, ionic liquids, extraction, binodal curve, liquid-liquid equilibrium, partition model, protein

摘要：

为了研究木瓜蛋白酶在[C_nmim]BF₄-NaH₂PO₄双水相体系中的分配行为, 在298.15 K条件下利用浊点法测定了[C_nmim]BF₄-NaH₂PO₄双水相体系的双节线和液液相平衡数据, 建立了木瓜蛋白酶在该体系中的三维分配模型。利用Merchuk方程、Othmer-Tobias方程和Bancroft方程分别关联了双节线数据、液液相平衡数据, 拟合度分别在0.975、0.994以上, 结果满意。木瓜蛋白酶分配系数的对数与该体系上相的离子液体浓度和下相的盐浓度相关度都较高, 故通过Matlab建立了三者之间的分配模型, 实验值和预测值之间的相对偏差均在5%以内, 表明该模型能有效地预测木瓜蛋白酶在[C_nmim]BF₄-NaH₂PO₄双水相体系中的分配行为。

关键词: 木瓜蛋白酶, 离子液体, 萃取, 双节线, 液液相平衡, 分配模型, 蛋白质