人顶体酶活性腔性质及与抑制剂的结合模式

Characterization of Human Acrosin Active Site and Binding Modes with Its Inhibitors

顶体酶是目前抗生育药物的一个潜在靶点.在前期同源模建人顶体酶三维结构复合物的基础上,采用多重拷贝同时搜寻(MCSS)等方法对人顶体酶活性腔进行分析.结果显示,活性腔的P1,P2和G3个区域均具有较大极性,且P1对抑制剂结合尤为重要.另外,G和P1边缘及P2底部还具有一定疏水性,且其中的部分重要残基还能与配体形成氢键作用和静电作用.MCSS计算结果确定的关键配体结合位点与人顶体酶复合物结构和定点突变实验结果相吻合.在此基础上用分子对接方法将6个人顶体酶代表性抑制剂对接入活性腔,阐明其结合模式,确定与配体结合相关的关键残基.

Acrosin is a promising target for contraceptive agents. Based on the previous homology modeling of human acrosin, the multiple copy simultaneous search（MCSS） methodology was used to explore the active site of human acrosin. The results show that all of three subsites（P1, P2 and G） are polar zones, and P1 is crucial for inhibitors′ binding. In addition, the edge of P1 and G as well as the bottom of P2 are hydrophobic, in which several important residues form hydrogen-binding interactions and electrostatic interactions. The key residues for ligand binding confirmed by MCSS calculations were consistent with the 3D structure of human acrosin complex and the experiments of site-directed mutagenesis on the animals. On the basis of above results, six of acrosin inhibitors, were docked into the active site of the human acrosin to elucidate their binding mode and the critical residues involved in binding. Our studies provide a basis for the rational design of novel acrosin inhibitors and the discovery of novel contraceptive drugs with high potency.