双水相萃取藻蓝蛋白的机理

Mechanism of the aqueous two-phase extraction of phycocyanin

采用荧光光谱的方法对双水相萃取藻蓝蛋白(PC)的机理进行了研究。不同分子量的聚乙二醇(PEG)对PC均有荧光猝灭作用。PEG与PC相互作用的热力学研究结果表明,PEG1000与PC的结合常数大于PEG2000和PEG4000,两者是熵驱动下的疏水作用力结合。不同的无机盐对PEG1000与PC结合的影响不同,其中Na2SO4使PEG1000-PC体系熵增效果最显著。同步荧光光谱的研究表明,PEG1000使PC色氨酸残基微环境的疏水性增强;Na2SO4通过促进PEG1000与PC的结合而使色氨酸残基微环境的疏水性进一步增强。单因素扫描实验的结果表明,PEG1000/Na2SO4体系双水相萃取纯化藻蓝蛋白(PC)的能力最强,符合PEG1000与PC分子相互作用的热力学规律。

The mechanism for aqueous two-phase extraction of phycocyanin （PC） was studied using florescence spectrum. The fluorescence of PC can be quenched by the addition of PEG despite the variation in molecular weights of PEGs. The thermodynamic investigation found that the binding constant between PEG1000 and PC was higher than that between PEG2000 and PEG4000. The binding between PEG and PC was built through hydrophobic interaction driven by entropy. Furthermore, compared to other inorganic salts tested,the addition of Na2SO4 showed the most positive impact on entropy increase,promoting the combinative interaction between PEG and PC. Moreover,the investigations on synchronous fluorescence spectroscopy found that the hydrophobicity of micro-environment around tryptophan residues was enhanced by the presence of PEG1000,and the hydrophobicity of micro-environment was increased further by the addition of Na2SO4. The single-factor experiments demonstrated that PEG1000/Na2SO4is the optimum aqueous two-phase extraction system in thermodynamics and practice for obtaining phycocyanin with the highest purity.