金属离子对花椒毒酚结合牛血清白蛋白体系的影响

Interactions Between Drugs and Bovine Serum Albumin in the Presence of Metal Ions by Spectral Methods

运用荧光猝灭光谱(FS)、圆二色光谱(CD)研究了花椒毒酚(XAL)对牛血清白蛋白(BSA)的相互作用以及不同金属离子对XAL-BSA体系的影响。在290、297和304 K的温度下扫描XAL-BSA体系荧光光谱,采用Stern-Volmer方程计算得到各相应温度下XAL对BSA的猝灭速率常数(kq)分别为6.316×10^(13)、4.402×10^(13)和3.554×10^(13)L/(mol·s)。研究结果表明:XAL能够猝灭BSA的荧光强度,且猝灭机理为XAL与BSA形成复合物的静态猝灭。在297 K温度下,XAL与BSA的结合常数为3.47×105L/mol,加入金属离子后对XAL与BSA的结合常数均有不同程度的影响。F9ster偶极-偶极非辐射能量转移理论得出:BSA中色氨酸残基与XAL的作用距离(r)为5.29 nm,当加入金属离子后,BSA中色氨酸残基分别与XAL的r均不同程度的降低。圆二色光谱(CD)表明XAL与BSA相互作用后改变了BSA的二级结构,α-螺旋结构的百分比减少,当加入金属离子后,进一步诱导BSA的二级结构变化,α-螺旋结构的百分比进一步减少。

The mechanisms of the interaction between xanthotoxol（ XAL） and bovine serum albumin（ BSA） were investigated by fluorescence and circular dichroism（ CD） spectrometry,as well as the effects of common metal ions（ Fe^3 ＋,Cu^2 ＋,Zn^2 ＋,Cr^3 ＋）on the XAL-BSA binding. The quenching constants（ kq） calculated by Stern-Volmer equation under 290,297 and 304 K were6. 316 × 10^13,4. 402 × 10^13 and 3. 554 × 10^13 L/（ mol·s）,respectively. The result indicated that XAL could quench the intrinsic fluorescence of BSA strongly,and the quenching mechanism was static quenching process. The binding constant（ K） of XAL to BSA at 297 K was 3. 47 × 105 L/mol. The addition of metal ions changed the binding constant. The distance between the tryptophan residues in BSA and XAL was 5. 29 nm by using F9 ster＇s equation,and it decreased after interaction with metal ions.The CD spectrometry demonstrated that the secondary structure of BSA changed after its interaction with XAL,and α-helix content decreased; the secondary structure of BSA was also changed by addition of metal ions and α-helix content furtherreduced.