Chemical-biological characterization of a cruzain inhibitor reveals a second target and a mammalian off-target
Chemical-biological characterization of a cruzain inhibitor reveals a second target and a mammalian off-target
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DOI：
10.3762/bjoc.9.3
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发表时间：
2013-01-04
影响因子：
2.7
通讯作者：
Renslo, Adam R.
中科院分区：
文献类型：
--
作者：
Choy, Jonathan W.;Bryant, Clifford;Renslo, Adam R.
抑制克氏锥虫半胱氨酸蛋白酶克氏蛋白酶已被提出作为治疗恰加斯病的一种治疗方法。迄今为止研究得最好的cruzain抑制剂是乙烯基砜K777(1)，它已被证明在恰加斯病的动物模型中有效。最近的结构-活性研究旨在解决1的潜在危害，现在已经产生了类似物，如N-[(2S)-1-[[(E,3S)-1-（苯磺酰基）-5-苯基戊-1-烯-3-基]氨基]-3-（4-甲基苯基）-1-氧丙基-2-基]吡啶-4-羧酰胺(4)，其浓度比1低10倍。我们现在发现4的锥虫活性主要来自对克氏锥虫14- α -去甲基化酶（TcCYP51）的抑制，TcCYP51是一种参与寄生虫麦角甾醇生物合成的细胞色素P450酶。化合物4也抑制哺乳动物CYP异构体，但浓度低于体外显著抑制哺乳动物CYP所需的浓度时具有锥虫作用。利用1衍生的基于活性的探针，化学蛋白质组学方法被用来鉴定哺乳动物组织蛋白酶B是1和4的潜在重要脱靶蛋白。计算对接研究和对4个截断类似物的评估揭示了TcCYP51结合的结构决定因素，这些信息将有助于进一步优化这类新型抑制剂。
Inhibition of the Trypanosoma cruzi cysteine protease cruzain has been proposed as a therapeutic approach for the treatment of Chagas' disease. Among the best-studied cruzain inhibitors to date is the vinylsulfone K777 (1), which has proven effective in animal models of Chagas' disease. Recent structure-activity studies aimed at addressing potential liabilities of 1 have now produced analogues such as N-[(2S)-1-[[(E,3S)-1-(benzenesulfonyl)-5-phenylpent-1-en-3-yl]amino]-3-(4-methylphenyl)-1-oxopropan-2-yl]pyridine-4-carboxamide (4), which is trypanocidal at ten-fold lower concentrations than for 1. We now find that the trypanocidal activity of 4 derives primarily from the inhibition of T. cruzi 14-alpha-demethylase (TcCYP51), a cytochrome P450 enzyme involved in the biosynthesis of ergosterol in the parasite. Compound 4 also inhibits mammalian CYP isoforms but is trypanocidal at concentrations below those required to significantly inhibit mammalian CYPs in vitro. A chemical-proteomics approach employing an activity-based probe derived from 1 was used to identify mammalian cathepsin B as a potentially important off-target of 1 and 4. Computational docking studies and the evaluation of truncated analogues of 4 reveal structural determinants for TcCYP51 binding, information that will be useful in further optimization of this new class of inhibitors.