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目的研究丹参酚酸与牛血清白蛋白的结合反应特性及其结构相关性。方法运用荧光和紫外光谱法研究了4种小分子天然丹参酚酸类化合物迷迭香酸、紫草酸、丹参酚酸A、丹参酚酸B(SAⅠ~Ⅳ)与牛血清白蛋白(BSA)的相互作用。结果计算得到各SA-BSA结合体系的静态表观结合常数(KA)、结合位点数(n)、能量转移效率(E)、空间距离(r)及热力学常数ΔG、ΔH和ΔS。4种丹参酚酸均能与BSA结合形成非共价复合物,通过静态猝灭和非辐射能量转移共同导致BSA内源荧光的猝灭。结论丹参酚酸A(SAⅢ)主要通过疏水作用力与BSA结合,而其余3种丹参酚酸与BSA的结合则主要由氢键和范德华力驱动。SA-BSA相互作用体系的结合强度可以用综合反应参数[Y=lg(KA×E×n/r)]来表征,其在数值上按SAⅢ→SAⅣ→SAⅡ→SAⅠ的顺序递减,并与分子中所含游离羟基数目和分子体积等结构特性密切相关,可以利用脂-水分配系数(clogP)和单位相对分子质量下的拓扑分子极性表面积(tPSA/Mr)来预测丹参酚酸化合物与蛋白的结合程度。
Objective To study the binding reaction and structure of salvianolic acid with bovine serum albumin (BSA). Methods Fluorescence and UV spectroscopy were used to study the effects of four small molecules of natural salvianolic acids rosmarinic acid, lithospermic acid, salvianolic acid A, salvianolic acid B (SAⅠ ~ Ⅳ) and bovine serum albumin (BSA) interaction. Results The static apparent binding constant (KA), number of binding sites (n), energy transfer efficiency (E), spatial distance (r) and thermodynamic constants ΔG, ΔH and ΔS were calculated for each SA-BSA binding system. All four kinds of salvianolic acids can combine with BSA to form non-covalent complex, which quenches endogenous fluorescence of BSA through static quenching and non-radiative energy transfer. Conclusion Salicylic acid SA (SA Ⅲ) binds to BSA mainly through hydrophobic interaction, while the binding of the other three salvianolic acids to BSA is mainly driven by hydrogen bonds and van der Waals forces. The binding strength of the SA-BSA interaction system can be characterized by the comprehensive reaction parameter [Y = lg (KA × E × n / r)], which decreases in value in the order of SAIII → SAIV → SAII → SAI, Is closely related to the structural characteristics such as the number of free hydroxyl groups and the molecular volume. The polar surface area (tPSA / Mr) of the topological molecules can be predicted by using the coefficient of lipid-water partition coefficient (clogP) and unit relative molecular mass The degree of combination.