聚乙烯醇与牛血清白蛋白的相互作用及对其构象的影响

Interaction Between PVA and BSA and Its Influence on the Conformation of BSA

在生理条件下,使用凝胶过滤色谱、荧光光谱法、差示扫描量热分析和傅里叶变换红外光谱法(FTIR)研究了牛血清白蛋白(BSA)与聚乙烯醇(PVA)的相互作用.实验结果表明,PVA与BSA结合形成复合物,在其相互作用过程中,BSA色氨酸的发射荧光部分被猝灭,但是,相互作用并没有明显改变色氨酸的微环境;差示扫描量热分析结果提示,BSA与PVA之间的相互作用可能破坏了PVA或BSA的分子内作用力;用红外光谱法结合可增强分辨率的傅里叶去卷积技术和高斯曲线拟合技术共同用于对BSA与PVA复合物冻干粉中BSA酰胺Ⅰ带的定量分析,发现冻干粉BSA分子中与分子间相互作用相关的β-折叠组分含量明显减少,但是,可用于衡量冻干状态蛋白质结构完整性的α-螺旋组分含量没有降低.对冷冻干燥后样品中的可溶性BSA分析结果提示,PVA可以保护BSA冷冻干燥过程中的稳定性.

Gel filtration chromatography, fluorescence spectrophotometry, differential scanning calorimetry （DSC） and Fourier transform infrared spectrophotometry （FTIR） were used to investigate the interaction between polyvinyl alcohol（PVA） and bovine serum albumin （BSA） under physiological conditions. The results show that BSA form complex with PVA. During BSA interaction with PVA, emission fluorescence derived from tryptophan of BSA was partially quenched upon binding to PVA. However, microenvironment of tryptophan was not changed during the binding process. The results of DSC suggest that the interaction of PVA with BSA maybe reduce the intramolecular interaction of BSA or PVA. FTIR spectrometry was combined with resolution enhancement technique Fourier deconvolution and Gaussian curve-fitting procedures to quantitate the spectral information from the amide I bands of BSA within the freeze-dried mixture of PVA and BSA. The results show that the interaction of PVA with BSA affected only the β-sheet content but not α-helix, which is usually used as an indicator of the protein structural integrity in lyophilized state. Analysis of the BSA within the mixture of BSA and PVA suggest that interaction of PVA with the BSA maybe preserve the stability of BSA during lyophilization process.