第一代树枝状聚(胺-酯)与牛血清白蛋白相互作用的荧光光谱法研究

摘要

在生理条件下用荧光光谱法研究了第一代树枝状聚(胺-酯)[PAE(NH2)8]与牛血清白蛋白(BSA)间的相互作用.结果表明,加入PAE(NH2)8后,BSA发生荧光猝灭,其猝灭机制属于静态猝灭,通过计算得到PAE(NH2)8与BSA作用的动态消光常数为1.64 L/mmol.通过同步荧光、红边激发荧光位移法等方法的研究发现,PAE(NH2)8的存在会改变BSA的构象,使色氨酸残基周围变得更加疏水.此外还考察了体系的pH值和离子强度对PAE(NH2)8与BSA相互作用的影响,发现静电作用是两者结合的主要作用机制.研究了金属离子Cu2+、Fe3+对PAE(NH2)8与BSA之间相互作用的影响.研究表明不同的金属离子对PAE(NH2)8与BSA相互作用的影响不同,Fe3+降低了PAE(NH2)8与BSA的结合能力,而Cu2+对PAE(NH2)8与BSA之间相互作用几乎没有影响.而金属离子的存在并不改变两者的结合位点数,BSA和PAE(NH2)8之间的结合位点数均近似为1.27.%The interaction between the first generation of dendritic poly(amine-ester) PAE(NH2)8 and bovine serum albumin (BSA) under physiological condition was studied by fluorescence spectroscopy. The fluorescence intensity of BSA decreased after the addition of PAE(NH2)8 and the quenching mechanism was suggested as static quenching. The dynamic extinction constant of PAE(NH2)8 with BSA was calculated to be 1. 64 L/mmol. At the same time, synchronous fluorescence and red edge excitation shift were adopted to review the conformational changes of BSA influenced by PAE(NH2)8, and the results indicated that PAE(NH2)8 can change the conformation of BSA, and make the trypto-phan residue become more hydrophobic. In addition, this article also examined the influence of pH and ionic strength on the interactions, from which it is concluded that electrostatic interaction plays major roles in the binding process. The effect of Cuz+ and Fe3+ on the interaction between the den-drimer and the BSA was studied, and the results show that different metal ions have different affect on the interaction between dendrimers and BSA. Fe3+ decreases the binding capacity between den-drimer and BSA, but Cu2+ has little effect. Metal ions do not change the binding sites of PAE(NH2)8 and BSA, which is approximately 1. 27.