邻苯二甲酸酯与蔗糖转化酶的互用机制

Interaction between phthalic acid esters and invertase

本研究以邻苯二甲酸酯(phthalic acid esters,PAEs)和蔗糖转化酶为试验材料,采用同步荧光光谱、共振光散射光谱(RLS)、分子平均粒径、分子对接模拟、分子动力学模拟、酶活性和酶促反应动力学,探究PAEs与蔗糖转化酶的微观作用机制.结果表明,随着PAEs浓度的增加,蔗糖转化酶的RLS强度和分子平均粒径逐渐降低;PAEs主要通过疏水作用与蔗糖转化酶活性中心氨基酸残基结合,并通过氢键作用锁定结合取向;PAEs导致蔗糖转化酶的RMSD值降低;PAEs污染导致蔗糖转化酶酶活性显著降低(P<0.05),并使得其反应动力学参数Km和Vmax减小,属于反竞争性抑制机制.研究表明,PAEs与蔗糖转化酶形成PAEs-酶复合物,改变了蔗糖转化酶的分子构象,并通过反竞争性抑制机制抑制蔗糖转化酶的酶活性.

In this study,mechanisms of the interaction between phthalic acid esters(PAEs)and invertase were investigated using resonance light scattering spectroscopy(RLS),particle size measurement,molecular docking,molecular dynamics simulation,enzyme activity assay and reaction kinetic experiment.The results showed that the RLS intensity and average particle size of invertase were decreased gradually with the increase of PAEs concentration.PAEs mainly bound with the amino acid residues of the catalytic domain of invertase by hydrophobic force,and locked the binding orientation by hydrogen bonding.Furthermore,the RMSD of invertase decreased by PAEs.In addition,the enzyme activity of invertase was inhibited by PAEs and the reaction kinetic parameters,Km and Vmax decreased,which belonged to the anti-competitive inhibition mechanism.We concluded that PAEs interacted with invertase to form PAEs-enzyme complex by hydrophobic force and hydrogen bond,which changed the conformations of invertase,and then inhibited the enzyme activities by anti-competitive inhibition mechanism.