荧光光谱法研究链格孢霉毒素TeA与血清白蛋白的互作机理

Interaction Mechanism between Alternaria mycotoxins TeA and Serum Albumin by Fluorescence Spectroscopy

链格孢霉毒素是由链格孢霉菌属(Alternaria species)产生的次级代谢产物,在水果、蔬菜以及粮食作物中污染率极高,可通过多种途径进入人类食物链,引发食品安全问题。为研究链格孢霉毒素细交链格孢菌酮酸(Tenuazonic Acid,TeA)在动物体内的吸收、分布、转运及代谢,本文采用稳态荧光光谱、同步荧光光谱、3D荧光光谱和圆二色光谱法等方法对TeA与人血清白蛋白(Human serum albumin,HSA)和牛血清白蛋白(Bovine serum albumin,BSA)之间的分子相互作用及机理进行探究。结果表明,在模拟血液生理pH条件下(pH7.40)TeA对两种模式血清白蛋白均产生了静态猝灭作用,形成了稳定的非荧光复合物;结合位点数表明TeA和血清白蛋白以1:1比例结合;热力学分析表明TeA和两种血清白蛋白之间相互作用涉及的作用力主要为疏水作用力(ΔH>0,ΔS>格孢霉毒素0);3D荧光、同步荧光结果表明TeA的结合使两种血清白蛋白的氨基酸残基微环境极性改变;圆二色谱表明TeA与血清白蛋白结合使HAS与BSA中的α-螺旋结构含量增加。TeA与HAS和BSA的结合可自发进行,且有较强的结合能力,结合后两种血清白蛋白的构象均发生变化。该结果为链格孢毒素在动物体内暴露和代谢动力学研究等进一步研究打下坚实基础。

Alternaria mycotoxins,as a secondary metabolite produced by Alternaria species,widely contaminates fruits,vegetables and food crops and often enters the human food chain through multiple channels,causing food safety issues.In order to study the absorption,distribution,transport and metabolism of tenuazonic acid(TeA)in animals,steady state fluorescence spectrum,synchronous fluorescence spectrum,3D fluorescence spectrum and circular dichrochromatic spectroscopy were used to determine the molecular interaction and mechanism between TeA and human serum albumin(HSA)and orbovine serum albumin(BSA).Results showed that:TeA displayed a static quenching effect on both types of serum albumin under the simulated blood physiological pH of 7.40 to form a stable non-fluorescent complex,the number of binding sites indicated that TeA and serum albumin combined data ratio of 1:1.Thermodynamic analysis demonstrated that the forces involved in the interaction between TeA and two serum albumins were mainly hydrophobic forces(ΔH>0,ΔS>0).3D fluorescence and synchronous fluorescence results suggested that the combination of TeA changed the microenvironment polarity of the amino acid residues of serum albumin.Circular dichroism showed that the combination of TeA and serum albumin increased the content ofα-helical structure in HSA and BSA.The binding of TeA to HAS and BSA could occur spontaneously and had a strong binding capacity to change the conformation of both serum albumin after binding.The results would lay a solid foundation for further studies such as exposure and metabolic dynamics of streptospore toxin in animals.