Almeida Nara L, Oliveira Cristiano L P, Torriani Iris L, Loh Watson
Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, 13083-970 Campinas, SP, Brazil.
Colloids Surf B Biointerfaces. 2004 Oct 10;38(1-2):67-76. doi: 10.1016/j.colsurfb.2004.08.004.
This work reports investigations aiming at verifying the occurrence of specific interactions between lysozyme or bovine serum albumin (BSA) and poly(ethylene oxide) and its copolymers with poly(propylene oxide). Thermal stability of these proteins, followed by means of high sensitivity DSC, was found to be mostly unaffected by the presence of these polymers. Chromatographic experiments (reverse-phase HPLC and size exclusion chromatrography) did not reveal any sign of specific interaction for these mixtures, either. Isothermal titration calorimetry revealed an increase in enthalpy for the mixtures, represented by a positive enthalpy of transfer for these proteins from buffer to polymer solutions. Moreover, SAXS analyses confirmed that at ambient temperatures these polymers do not affect lysozyme structure. In summary, no evidence is found to support earlier suggestions that some kind of complex could be formed between these proteins and poly(ethylene oxide) or its copolymers, but the present results suggest the occurrence of entropically driven hydrophobic effects.
本研究报告了旨在验证溶菌酶或牛血清白蛋白（BSA）与聚环氧乙烷及其与聚环氧丙烷的共聚物之间特定相互作用是否存在的调查。通过高灵敏度差示扫描量热法（DSC）跟踪发现，这些聚合物的存在对这些蛋白质的热稳定性基本没有影响。色谱实验（反相高效液相色谱和尺寸排阻色谱）也未显示这些混合物存在任何特定相互作用的迹象。等温滴定量热法显示混合物的焓增加，表现为这些蛋白质从缓冲液转移到聚合物溶液时的正转移焓。此外，小角X射线散射（SAXS）分析证实，在环境温度下这些聚合物不会影响溶菌酶的结构。总之，没有证据支持早期关于这些蛋白质与聚环氧乙烷或其共聚物之间可能形成某种复合物的说法，但目前的结果表明存在熵驱动的疏水效应。
