光谱法研究两种抗菌类药物对牛血清白蛋白结构变化的影响

摘要

利用荧光猝灭光谱、同步荧光光谱、三维荧光光谱、紫外-可见吸收光谱及圆二色谱法研究了磺胺甲恶唑(Sulfamethoxazole,SMX)、磺胺二甲嘧啶(Sulfamethazine,SMZ)对牛血清白蛋白(Bovine serum albumin,BSA)结构的影响。荧光猝灭实验结果表明SMX和SMZ可以使BSA发生荧光猝灭；通过同步荧光光谱、三维荧光光谱和紫外-可见光谱实验数据定性的证实了SMX和SMZ的加入会使BSA的构象发生变化,并且通过紫外-可见光谱的实验结果可知SMX和SMZ与BSA之间的作用机理为静态猝灭。此外,由圆二色谱法得到的定量结果可知：当SMX或SMZ与BSA之间的摩尔浓度比为4∶1时,SMX可使BSA的α-螺旋结构含量由53．77%降低到51．82%；SMZ可使BSA的α-螺旋结构含量由53．77%降低到47．59%。%Structural changes of bovine serum albumin(BSA)caused by sulfamethoxazole(SMX)and sulfamethazine(SMZ)were studied using fluorescence quenching spectroscopy,Synchronous fluorescence spectroscopy,three-dimensional fluorescence spectros-copy,UV-vis absorption spectroscopy and circular dichroism spectroscopy(CD). The experiment results obtained from fluorescence quenching spectra data indicated that the fluorescence intensity of BSA was quenched by the gradual addition of SMX/SMZ;Experi-mental results obtained from the Synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and UV-vis absorption spectroscopy qualitatively confirmed that the secondary structure of BSA was altered in the presence of SMX/SMZ in a-queous solution,and the quenching mechanisms of SMX/SMZ and BSA were both static quenching process confirmed by UV-vis ab-sorption spectroscopy. Furthermore,the bindings of SMX/SMZ to BSA caused the changes of protein secondary structures,with the loss of α-helical stabilities. The calculating results exhibited reductions ofα-helix structures from 53. 77%to 51. 82%and 53. 77%to 47. 59%at molar ratios SMX/SMZ to BSA of 4∶1,respectively.