芘与人血清白蛋白和牛血清白蛋白结合位点微环境极性的差异

利用芘(Pyr)的微环境极性探针性质, 采用稳态荧光光谱、 荧光共振能量转移技术结合分子对接法, 对比分析了Pyr分别与人血清白蛋白(HSA)和牛血清白蛋白(BSA)作用机制的差异. 结果表明, HSA和BSA中Pyr的I₁/I₃平均值分别为1.36和0.92; Pyr与HSA和BSA的结合常数分别为1.86×10⁷和1.71×10⁵ L/mol; Pyr与HSA和BSA中色氨酸残基表观距离分别为2.37和2.34 nm. Pyr在HSA和BSA中不同的结合位点位于ⅠB子域和ⅠA子域, 其结合位点周围氨基酸残基的极性是影响Pyr I₁/I₃值的主要原因之一. 实验证实Pyr与HSA和BSA结合作用位点处的微环境极性存在差异.

Interactions of Pyrene with Human Serum Albumin and Bovine Serum Albumin:Microenvironmental Polarity Differences at Binding Sites

The interactions of pyrene（Pyr）， a microenvironmental hydrophobic fluorescent probe， with human serum albumin（HSA） or bovine serum albumin（BSA） were investigated using steady-state fluorescence， fluorescence resonance energy transfer technology， and molecular docking methods. It was observed that the average values of I₁/I₃ of the Pyr in the presence of HSA or BSA are 1.36 and 0.92， respectively. The binding constants of Pyr with HSA or BSA has been decreased from 1.86×10⁷ L/mol ^{to 1.71×105 L/mol. The apparent distances of Pyr to tryptophan residues in HSA or BSA were calculated to be 2.37 and 2.34 nm. The binding sites of Pyr in HSA or BSA were located in subdomain ⅠB and subdomains ⅠA， respectively. The polarity of amino acid residues around the binding sites was one of the main factors affecting the I₁/I₃ value of Pyr. The experimental results suggested that there were significant differences in the binding sites and its microenvironmental polarity of BSA and HSA with Pyr.}