STRUCTURAL STUDIES OF AIDS RESPONSIVE DRUGS

描述：（改编自申请人的摘要）提出， Pc响应性抗叶酸剂的结合选择性是特异性的结果。 酶与结合抑制剂的相互作用。 申请人将对此进行测试 通过比较两者的三维晶体结构， 人和Pc二氢叶酸还原酶与辅因子NADPH复合， PC选择性抗叶酸剂，如PTX，TMQ和TMP，以检查是否 观察到的结构变化与抑制剂选择性相关。 这些数据的分析将提供分子水平的细节， 分子-酶的几何构型、氢键、构象和 特定的活性位点残基，特别是 人和PcDHFR之间F31 I和N64 F取代在调节Pc中 选择性 分子置换X射线晶体学技术 方法将被用来解决这些晶体结构。 的理由 这一拟议的研究是，结构要求的差异 对于抗叶酸剂与人和卡氏肺孢子虫的结合， 用于基于结构的药物设计，具有潜在的新抗叶酸剂 作为艾滋病佐剂。 由于选择性显然只需要很小的变化 在酶抑制剂几何学中，研究人员建议寻找微妙的 一系列仔细测定的DHFR晶体结构的差异 与Pc选择性抗叶酸剂的复合物。 三是知人知面不知心。 需要确定酶抑制剂复合物的三维结构 Pc的选择性和作用机制。 基于理性结构的 将合作设计新的Pc选择性抗叶酸剂 与迪克讷大学的Aleem Gangjee博士合作， 抗叶酸剂和印第安纳州大学的Sherry Queener博士， 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.