SYNTHESIS OF CRUZAIN INHIBITORS

这个项目的具体目标是设计和合成改进的 半胱氨酸蛋白酶的活性位点定向抑制物 克氏锥虫。多肽模拟物和非多肽抑制剂将 借助于源自以下方面的见解进行设计： (I)Fletterick和McGrath最近解决的X射线结构， 其在活性部位具有共价结合的Z-Phe-Ala-FMK抑制剂： (Ii)二肽的结构要求的知识 McKerrow和他的同事已经证明了氟甲基酮(FMK) 是精制克鲁扎因的有效、不可逆转的抑制剂，也是 在体内积极对抗克氏锥虫；以及， (Iii)源自船坞的结构资料，而非由船坞产生 源于Cohen和Cohen工作的多肽铅抑制剂结构 戒指。 此外，还合成了一类新型的半胱氨酸蛋白酶抑制剂。 题材将得到开发。具体地说，加入了抑制剂 将合成环氧丙酰基酮(EPK)亚结构，并 由我们的寄生虫学和生化合作者麦克罗进行评估 以及加州大学旧金山分校的恩格尔。进一步修改和优化 最初的EPK抑制剂将被执行，如果有希望的活性 观察到了克鲁扎因抑制剂。 这些工作的重点是确定Lead的修改 已确定的抑制剂结构(见背景和意义 节)，以提高它们在体内的使用。吸收等因素 从口腔途径，消除可能有助于 毒性副反应，并增强其活性和特异性 针对靶标蛋白水解酶的抑制剂将进行评估。 在涉及我们综合小组的迭代周期中，计算机建模 组(Cohen)、蛋白质结构组(McGrath、Fletterick和 Craik)，以及该程序的寄生虫学和生化组件 (McKerrow和Engel)。这些共同的努力将导致设计和 合成更特异和更有效的克鲁萨因抑制剂。

The specific aim of this program is to design and synthesize improved active site directed inhibitors of cruzain, the major cysteine protease of Trypanosoma cruzi. Peptide mimetics and non-peptidic inhibitors will be designed with the aid of insights deriving from: (i) The X-ray structure recently solved by Fletterick and McGrath, which has a covalently bound Z-Phe-Ala-FMK inhibitor at the active site: (ii) Knowledge of the structural requirements of the dipeptide fluoromethyl ketones (FMK) that McKerrow and coworkers have demonstrated to be potent, irreversible inhibitors of purified cruzain, and also to be active in vivo against Trypanosoma cruzi; and, (iii) Structural information deriving from the DOCK-generated, non- peptidic lead inhibitor structures deriving from the work of Cohen and Ring. In addition, a new class of cysteine protease inhibitors based on the E- 64 motif will be developed. Specifically, inhibitors incorporating epoxypropionyl ketone (EPK) substructures will be synthesized and evaluated by our parasitology and biochemistry collaborators, McKerrow and Engel, at UC San Francisco. Further modifications and optimization of the initial EPK inhibitors will be performed if promising activity as cruzain inhibitors is observed. The focus of these efforts is to identify modifications of the lead inhibitor structures already identified (see Background and Significance Section) so as to enhance their use in vivo. Factors such as absorption from the oral route, eliminating functional groups that may contribute to toxic side reactions, and enhancing the activity and specificity of the inhibitors against the targeted protease, cruzain, will be evaluated in iterative cycles involving our synthesis group, the computer modeling group (Cohen), the protein structure groups (McGrath, Fletterick and Craik), and the parasitology and biochemistry components of this program (McKerrow and Engel). These combined efforts will lead to the design and synthesis of ever more specific and potent cruzain inhibitors.