二苯-α-吡喃酮类链格孢霉毒素和人血清白蛋白的相互作用及机理探究

为探究链格孢酚单甲醚(AME)和链格孢酚(AOH)这两种二苯-α-吡喃酮类链格孢霉毒素与人血清白蛋白(HSA)之间的分子相互作用及机理,本研究模拟血液生理pH值,采用稳态荧光光谱、同步荧光光谱、3D荧光光谱以及圆二色光谱等方法研究两者之间的相互作用。结果表明,AME和AOH与HSA相互作用均发生了静态猝灭,具有较高亲和力,以氢键和范德华力(ΔH<0,ΔS<0)结合形成1:1复合物,互作过程中这两种类毒素破坏了人血清白蛋白中稳定二级结构的氢键网络,使蛋白二级结构展开,且AME和AOH使人血清白蛋白中的α-螺旋结构含量从48.93%分别减少至39.41%和44.01%,并使色氨酸残基极性降低、疏水性增加,但酪氨酸残基极性变化不大,即结合位点可能位于色氨酸残基所在的空腔(即结合位点I);AME对HSA的猝灭程度、猝灭常数(K_sv)及结合常数(K_a)均大于AOH,结合距离也更小(r_AME=2.56 nmAOH=2.60 nm)。本研究结果为进一步探究二苯-α-吡喃酮类链格孢霉毒素的毒代动力学和药代动力学,完善丰富其毒理学相关资料,以及进行风险评估和在食品中限量标准的制定提供了参考依据。

Investigation on Molecular Interaction Between of Alternariol Monomethyl Ether and Alternariol With Human Serum Albumin

In order to study molecular interaction and its mechanism between alternariol monomethyl ether (AME)/alternariol (AOH), as the typical mycotoxins of diphenyl-α -pyranone type of alternaria, and the human serum albumin (HSA), the steady-state fluorescence spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and circular dichroism spectroscopy were used under the physiological pH of blood. The results showed that AME and AOH can quench the fluorescence of human serum albumin by static quenching and form a 1:1 compound by hydrogen bonding with van der Waals forces. Due to the binding of AME/AOH to HSA, the hydrogen bond network and the secondary structure of HSA were damaged. Besides, the binding of AME and AOH also reduced the content of α-helix structure in HSA from 48.93% to 39.41% and 44.01%, respectively, which making the hydrophobicity of Trp residue polarity decreased. This indicated that the binding site of HSA for AME or AOH should be site I. The quenching degree of AME is higher and the binding distance is closer than that of AOH(r_AME=2.56 nmAOH=2.60 nm). It is suggested that AME has a stronger affinity with HSA. This paper provides a reference for the further study on the toxicokinetics and pharmacokinetics of this kind of mycotoxins and scientifically assess the health risk as well as the formulation of the corresponding limiting standards and regulations.