Identification of a new class of nonpeptidic inhibitors of cruzain
Identification of a new class of nonpeptidic inhibitors of cruzain
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DOI：
10.1021/ja710254m
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发表时间：
2008-05-21
影响因子：
15
通讯作者：
Ellman, Jonathan A.
中科院分区：
文献类型：
--
作者：
Brak, Katrien;Doyle, Patricia S.;Ellman, Jonathan A.
克氏锥虫是恰加斯病的病原体克氏锥虫的主要半胱氨酸蛋白酶，是开发新型化疗药物的一个有希望的靶点。为了开发有效的cruzain非肽类抑制剂，我们使用底物活性筛选（SAS）方法筛选了一个蛋白酶底物文库，该文库最初设计用于靶向同源的人蛋白酶组织蛋白酶s。接下来，基于结构的设计通过在cruzain的S3袋中引入额外的结合相互作用来进一步提高底物切割效率。然后通过引入基于半胱氨酸蛋白酶机制的药效团将优化的底物转化为抑制剂。抑制剂38被确定为可逆的，即使它含有乙烯砜药效团，这是有充分证据证明对肽抑制剂具有不可逆的cruzain抑制作用。以前未开发的-氯乙烯基砜药效团提供了机制洞察力，导致开发有效的不可逆酰基和芳基氧甲基酮cruzain抑制剂。对于这些抑制剂，效力并不仅仅取决于离开基团pK(a), 2,3,5,6-四氟苯氧甲基酮54被确定为最有效的抑制剂之一，其二级失活常数为147,000 s(-1) M-1。这种抑制剂完全从哺乳动物细胞培养物中根除克氏t型寄生虫，因此有可能导致新的恰加斯病化疗药物。
Cruzain is the major cysteine protease of Trypanosoma cruzi, which is the causative agent of Chagas disease and is a promising target for the development of new chemotherapy. With the goal of developing potent nonpeptidic inhibitors of cruzain, the substrate activity screening (SAS) method was used to screen a library of protease substrates initially designed to target the homologous human protease cathepsin S. Structure-based design was next used to further improve substrate cleavage efficiency by introducing additional binding interactions in the S3 pocket of cruzain. The optimized substrates were then converted to inhibitors by the introduction of cysteine protease mechanism-based pharmacophores. Inhibitor 38 was determined to be reversible even though it incorporated the vinyl sulfone pharmacophore that is well documented to give irreversible cruzain inhibition for peptidic inhibitors. The previously unexplored beta-chloro vinyl sulfone pharmacophore provided mechanistic insight that led to the development of potent irreversible acyl- and aryl-oxymethyl ketone cruzain inhibitors. For these inhibitors, potency did not solely depend on leaving group pK(a), with 2,3,5,6-tetrafluorophenoxymethyl ketone 54 identified as one of the most potent inhibitors with a second-order inactivation constant of 147,000 s(-1) M-1. This inhibitor completely eradicated the T. cruzi parasite from mammalian cell cultures and consequently has the potential to lead to new chemotherapeutics for Chagas disease.