Direct inhibition of GPX4 requires covalent modification of the active-site selenocysteine. While phenotypic screening has revealed that activated alkyl chlorides and masked nitrile oxides can inhibit GPX4 covalently, a systematic assessment of potential electrophilic warheads with the capacity to inhibit cellular GPX4 has been lacking. Here, we survey more than 25 electrophilic warheads across several distinct GPX4-targeting scaffolds. We find that electrophiles with attenuated reactivity compared to chloroacetamides are unable to inhibit GPX4 despite the expected nucleophilicity of the selenocysteine residue. However, highly reactive propiolamides we uncover in this study can substitute for chloroacetamide and nitroisoxazole warheads in GPX4 inhibitors. Our observations suggest that electrophile masking strategies, including those we describe for propiolamide- and nitrile-oxide-based warheads, may be promising for the development of improved covalent GPX4 inhibitors.

GPX4 的直接抑制需要活性位点硒代半胱氨酸的共价修饰。虽然表型筛选表明活化的烷基氯化物和掩蔽的腈氧化物可以共价抑制 GPX4，但缺乏对具有抑制细胞 GPX4 能力的潜在亲电弹头的系统评估。在这里，我们在几个不同的 GPX4 靶向支架上调查了超过 25 个亲电子弹头。我们发现，尽管硒代半胱氨酸残基具有预期的亲核性，但与氯乙酰胺相比，反应性减弱的亲电试剂无法抑制 GPX4。然而，我们在本研究中发现的高反应性丙炔酰胺可以替代 GPX4 抑制剂中的氯乙酰胺和硝基异恶唑弹头。我们的观察表明，亲电掩蔽策略，