An in silico screen of 350 000 commercially available compounds was conducted with an unbiased approach to identify potential malaria inhibitors that bind to the Plasmodium falciparum protein kinase 5 (PfPK5) ATP‐binding site. PfPK5 is a cyclin‐dependent kinase‐like protein with high sequence similarity to human cyclin‐dependent kinase 2 (HsCDK2), but its precise role in cell‐cycle regulation remains unclear. After two‐dimensional fingerprinting of the top scoring compounds, 182 candidates were prioritized for biochemical testing based on their structural diversity. Evaluation of these compounds demonstrated that 135 bound to PfPK5 to a similar degree or better than known PfPK5 inhibitors, confirming that the library was enriched with PfPK5‐binding compounds. A previously reported triazolodiamine HsCDK2 inhibitor and the screening hit 4‐methylumbelliferone were each selected for an analogue study. The results of this study highlight the difficult balance between optimization of PfPK5 affinity and binding selectivity for PfPK5 over its closest human homologue HsCDK2. Our approach enabled the discovery of several new PfPK5‐binding compounds from a modest screening campaign and revealed the first scaffold to have improved PfPK5/HsCDK2 selectivity. These steps are critical for the development of PfPK5‐targeting probes for functional studies and antimalarials with decreased risks of host toxicity.

中文翻译：

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恶性疟原虫蛋白激酶 5 (PK5) 抑制剂的计算机筛选和评估


采用公正的方法对 350 000 种市售化合物进行了计算机筛选，以确定与恶性疟原虫蛋白激酶 5 ( Pf PK5) ATP 结合位点结合的潜在疟疾抑制剂。 P f PK5 是一种细胞周期蛋白依赖性激酶样蛋白，与人细胞周期蛋白依赖性激酶 2 ( Hs CDK2) 具有高度序列相似性，但其在细胞周期调节中的确切作用仍不清楚。对得分最高的化合物进行二维指纹识别后，182 种候选化合物根据其结构多样性被优先进行生化测试。对这些化合物的评估表明，135 与Pf PK5 的结合程度与已知的Pf PK5 抑制剂相似或更好，证实该库富含Pf PK5 结合化合物。之前报道的三唑二胺Hs CDK2 抑制剂和筛选的 4-甲基伞形酮均被选择进行类似物研究。这项研究的结果强调了Pf PK5 亲和力的优化和Pf PK5 相对于其最接近的人类同源物Hs CDK2 的结合选择性之间的困难平衡。我们的方法通过适度的筛选活动发现了几种新的Pf PK5 结合化合物，并揭示了第一个具有改善的Pf PK5/ Hs CDK2 选择性的支架。这些步骤对于开发用于功能研究的Pf PK5 靶向探针和降低宿主毒性风险的抗疟药至关重要。