It has been recognized that the artificial chaperone system, cetyltrimethylammonium bromide and β-cyclodextrin, is effective for enhancing protein renaturation. In this work, we studied the effect of the artificial chaperone system and guanidinium chloride (GdmCl) on the oxidative renaturation of lysozyme at 0.21-1.05mg/mL, and a kineticmodel based on the competition between protein folding and aggregation was employed to express the renaturation process. The refolding rate constant increased, while the aggregation rate constant decreased, with increasing concentration of the artificial chaperones. With increasing GdmCl concentration (0.28-2M), both rate constants decreased, but there existed a specific GdmCl concentration that maximized the ratio of the two rate constants and thus the renaturation yield. The results obviously indicated the cooperative effect of GdmCl and the artificial chaperones on enhancing protein renaturation.

From the renaturation kinetics of denatured/reduced lysozyme assisted by the molecular chaperone GroEL, a simplified kinetic model was established based on the competition between protein folding and aggregation. In the presence of GroEL and ATP, the aggregate formation was a second order reaction. With 2mM ATP, a renaturation yield of 90% at a high renaturation rate was obtained when the molar ratio of GroEL to lysozyme was 1: 1.

Sorbitan trioleate was modified with Cibacron Blue F-3GA (CB) to create an affinity surfactant and to form affinity-based reverse micelles in nhexane. The partitioning equilibria and the extraction kinetics of lysozyme and bovine serum albumin (BSA) were then examined. The solubilization capacity of the reverse micellar system for lysozyme increased linearly with increasing the CB concentration from 0.1 to 0.5 mmol L−1. In contrast, the capacity for BSA at 0.5 mmol L-1 of coupled CB was only about one-fifth that for lysozyme. It indicates a strong steric hindrance effect of the micelles for the high molecular mass protein. The overall volumetric mass transfer coefficient of lysozyme in the forward extraction increased from 0.43×10−3 to 1.25×10−3 s−1 with increasing CB concentration from 0.1 to 0.5 mmol L−1. Due to the high molecular mass of BSA, its volumetric mass transfer coefficient in the forward extraction was only one-sixth that of lysozyme. The ratio of the coefficient in the back extraction to that in the forward extraction was less than 0.03, much lower than those in other micellar systems. It indicates that the interfacial resistance in this system was severer than in others.

Sorbitan trioleate (Span 85) modified with Cibacron Blue F-3GA (CB) was used as an affinity surfactant (CB-Span 85) to form affinity-based reversed micelles in n-hexane. It was found that the addition of hexanol to the reversed micellar system resulted in a significant increase in water content and hydrodynamic radius of the affinity-based reversed micelles. Moreover, the reversed micelles with hexanol revealed broader aggregation number distribution and larger average aggregation number than the reversed micelles without hexanol addition. This is considered to be due to the decreases in the micellar curvature and rigidity of the micellar interfacial layer and the increase in the micellar interfacial fluidity. Consequently, the solubilization capacity of lysozyme increased about 70% in the reversed micellar solution with 3 vol% hexanol. On the other hand, the capacity of BSA was only 30% increased under the same conditions due to its larger molecular size than lysozyme. Kinetic analysis revealed that the increase in the micellar interfacial fluidity in the presence of hexanol resulted in faster release of lysozyme from the micelles, thus leading to an increase of the overall volumetric mass transfer coefficient in the back extraction.

利用多角度激光光散射仪和圆二色谱仪研究小分子水溶性一元醇和多元醇对溶菌酶分子的稳定性以及对变性溶菌酶的空间构象和折叠复性的影响。发现在一元醇和二元醇溶液中溶菌酶分子的稳定性均随着醇浓度的增大而提高，而变性酶分子在醇溶液中形成过多的α螺旋和β折叠等二级结构不利于酶的折叠复性；只有较低浓度的多元醇和甲醇有辅助变性溶菌酶复性的作用，其中10%甲醇、20%甘油和30%乙二醇有利于促进酶的复性。