Identification and characterization of allophenylnorstatine-based inhibitors of plasmepsin II, an antimalarial target.
Identification and characterization of allophenylnorstatine-based inhibitors of plasmepsin II, an antimalarial target.
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DOI：
10.1021/bi0117549
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发表时间：
2002-02
期刊：
影响因子：
2.9
通讯作者：
A. Nezami;I. Luque;Tooru Kimura;Y. Kiso;E. Freire
中科院分区：
文献类型：
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作者：
A. Nezami;I. Luque;Tooru Kimura;Y. Kiso;E. Freire
Plasmepsin II是导致疟疾的疟原虫生命周期中的一种关键酶，疟疾每年折磨3亿多人。由于plasmepsin II抑制导致寄生虫饥饿，它已被认为是开发新的抗疟药物的重要靶点。在本文中，我们基于allophenylnorstatine支架，鉴定并表征了plasmepsin II的高亲和力抑制剂。最佳化合物KNI-727抑制plasmepsin II的K(i)为70 nM，相对于高度同源的人酶组织蛋白酶d的选择性为22倍。KNI-727与plasmepsin II结合的过程在焓和熵上都有利。在25℃时，结合焓δ δ为-4.4 kcal/mol，熵对吉布斯能的贡献δ δ δ为-5.56 kcal/mol。plasmepsin II的结构稳定性测量也被用来表征抑制剂的结合。在没有抑制剂的情况下进行的高灵敏度差示扫描量热实验表明，在pH 4.0时，plasmepsin II在63.3℃时发生热变性。酶的结构稳定性随着抑制剂浓度的增加而增加，抑制剂的结合能量可以定量地解释。通过对感染了恶性疟原虫的红细胞进行细胞毒性测定，证实了最佳化合物在杀死疟原虫方面的有效性。ec50在6 - 10微米（3-6微克/毫升）之间。这些实验证明了allophenylnorstatine支架在设计强效和选择性plasmepsin抑制剂方面的可行性。
Plasmepsin II is a key enzyme in the life cycle of the Plasmodium parasites responsible for malaria, a disease that afflicts more than 300 million individuals annually. Since plasmepsin II inhibition leads to starvation of the parasite, it has been acknowledged as an important target for the development of new antimalarials. In this paper, we identify and characterize high-affinity inhibitors of plasmepsin II based upon the allophenylnorstatine scaffold. The best compound, KNI-727, inhibits plasmepsin II with a K(i) of 70 nM and a 22-fold selectivity with respect to the highly homologous human enzyme cathepsin D. KNI-727 binds to plasmepsin II in a process favored both enthalpically and entropically. At 25 degrees C, the binding enthalpy (DeltaH) is -4.4 kcal/mol and the entropic contribution (-TDeltaS) to the Gibbs energy is -5.56 kcal/mol. Structural stability measurements of plasmepsin II were also utilized to characterize inhibitor binding. High-sensitivity differential scanning calorimetry experiments performed in the absence of inhibitors indicate that, at pH 4.0, plasmepsin II undergoes thermal denaturation at 63.3 degrees C. The structural stability of the enzyme increases with inhibitor concentration in a manner for which the binding energetics of the inhibitor can quantitatively account. The effectiveness of the best compounds in killing the malaria parasite was validated by performing cytotoxicity assays in red blood cells infected with Plasmodium falciparum. EC50s ranging between 6 and 10 microM (3-6 microg/mL) were obtained. These experiments demonstrate the viability of the allophenylnorstatine scaffold in the design of powerful and selective plasmepsin inhibitors.