STRUCTURAL STUDIES OF AIDS RESPONSIVE DRUGS

描述：(改编自申请人摘要)现建议 响应Pc的抗叶酸的结合选择性是特异性的结果 酶与结合抑制物的相互作用。申请者将对此进行测试 通过比较两者的三维晶体结构提出假说 人和Pc二氢叶酸还原酶与辅因子NADPH和 PC选择性抗叶酸盐，如PTX，TMQ和TMP，以检查 观察到的结构变化与抑制剂的选择性有关。 对这些数据的分析将提供分子水平的细节 抑制剂-酶的几何构型、氢键、构象和作用 特定的活性中心残基，特别是 人与PcDHFR之间的F31I和N64F在调节Pc中的替代 选择性。利用分子置换的X射线结晶学技术 将使用各种方法来解决这些晶体结构问题。其基本原理是 本文拟研究的是结构要求的差异 对于抗叶酸与人和卡氏肺孢子虫DHFR的结合 开发基于结构的药物设计具有潜力的新型抗叶酸 作为艾滋病佐剂。因为选择性显然只需要很小的改变 在酶抑制剂的几何构型中，研究人员建议寻找微妙的 DHFR一系列精心测定的晶体结构的差异 与Pc选择性抗叶酸的络合物。因此对三个方面的认识 酶-抑制剂复合体的空间结构需要确定 Pc的选择性和作用机理。以合理的结构为基础 将合作设计新的Pc选择性抗叶酸盐 与杜肯大学的Aleem Gangjee博士合作，他将合成新的 印第安纳大学的雪莉·奎纳博士将测量 他们的Pc活动。

DESCRIPTION: (Adapted from Applicant's Abstract) It is proposed that binding selectivity of Pc responsive antifolates is a result of specific enzyme interactions with bound inhibitors. The applicants will test this hypothesis by comparison of the three dimensional crystal structures of both human and Pc dihydrofolate reductase complexed with the cofactor NADPH and Pc selective antifolates such as PTX, TMQ and TMP, to examine whether observed structural changes are correlated to inhibitor selectivity. Analysis of these data will provide molecular level details of inhibitor-enzyme geometry, hydrogen bonding, conformation and the role of specific active site residues, especially the contribution by the substitution of F31I and N64F between human and PcDHFR, in modulating Pc selectivity. X-ray crystallographic techniques using molecular replacement methods will be used to solve these crystal structures. The rationale for this proposed research is that differences in the structural requirements for antifolate binding to human and Pneumocystis carinii DHFR can be exploited for structure-based drug design of new antifolates with potential as AIDS adjuvants. Since selectivity apparently requires only small changes in enzyme-inhibitor geometry, the investigators propose to look for subtle differences in a series of carefully determined crystal structures of DHFR complexes with Pc selective antifolates. Thus knowledge of the three dimensional structure of enzyme-inhibitor complexes are required to define the mechanism of Pc selectivity and action. The rational structure-based design of new Pc selective antifolates will be carried out in collaboration with Dr. Aleem Gangjee, Duquesne University, who will synthesize new antifolates and Dr. Sherry Queener, Indiana University, who will measure their Pc activity.