Retinaldehyde dehydrogenases belong to a superfamily of enzymes that regulate cell differentiation and are responsible for detoxification of anticancer drugs. Chemical tools and methods are of great utility to visualize and quantify aldehyde dehydrogenase (ALDH) activity in health and disease. Here, we present the discovery of a first-in-class chemical probe based on retinal, the endogenous substrate of retinal ALDHs. We unveil the utility of this probe in quantitating ALDH isozyme activity in a panel of cancer cells via both fluorescence and chemical proteomic approaches. We demonstrate that our probe is superior to the widely used ALDEFLUOR assay to explain the ability of breast cancer (stem) cells to produce all-trans retinoic acid. Furthermore, our probe revealed the cellular selectivity profile of an advanced ALDH1A1 inhibitor, thereby prompting us to investigate the nature of its cytotoxicity. Our results showcase the application of substrate-based probes in interrogating pathologically relevant enzyme activities. They also highlight the general power of chemical proteomics in driving the discovery of new biological insights and its utility to guide drug discovery efforts.

中文翻译：

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基于视网膜的视网膜细胞中脱醛醛脱氢酶谱分析探针的开发。

视黄醛脱氢酶属于调节细胞分化并负责抗癌药物排毒的酶的超家族。化学工具和方法对于可视化和定量健康和疾病中的醛脱氢酶（ALDH）活性非常有用。在这里，我们介绍了基于视网膜（视网膜ALDHs的内源性底物）的一流化学探针的发现。我们揭示了该探针在通过荧光和化学蛋白质组学方法定量检测一组癌细胞中ALDH同工酶活性方面的实用性。我们证明，我们的探针优于广泛使用的ALDEFLUOR分析，可以解释乳腺癌（干）细胞产生全反式维甲酸的能力。此外，我们的探针揭示了一种高级ALDH1A1抑制剂的细胞选择性谱，从而促使我们研究其细胞毒性的性质。我们的结果展示了基于底物的探针在询问病理相关酶活性中的应用。他们还强调了化学蛋白质组学在推动发现新的生物学见解方面的一般力量及其在指导药物发现工作中的效用。