Since their first use in bioconjugation more than 50 years ago, maleimides have become privileged chemical partners for the site-selective modification of proteins via thio-Michael addition of biothiols and, to a lesser extent, via Diels–Alder (DA) reactions with biocompatible dienes. Prominent examples include immunotoxins and marketed maleimide-based antibody–drug conjugates (ADCs) such as Adcetris, which are used in cancer therapies. Among the key factors in the success of these groups is the availability of several maleimides that can be N-functionalized by fluorophores, affinity tags, spin labels, and pharmacophores, as well as their unique reactivities in terms of selectivity and kinetics. However, maleimide conjugate reactions have long been considered irreversible, and only recently have systematic studies regarding their reversibility and stability toward hydrolysis been reported. This review provides an overview of the diverse applications for maleimides in bioconjugation, highlighting their strengths and weaknesses, which are being overcome by recent strategies. Finally, the fluorescence quenching ability of maleimides was leveraged for the preparation of fluorogenic probes, which are mainly used for the specific detection of thiol analytes. A summary of the reported structures, their photophysical features, and their relative efficiencies is discussed in the last part of the review.

中文翻译：

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通过基于马来酰亚胺的标记策略对生物分子的共价修饰

自从50多年来首次将其用于生物缀合以来，马来酰亚胺已成为通过化学硫代-迈克尔加成生物硫醇以及在较小程度上通过与生物相容性的Diels-Alder（DA）反应进行蛋白质的位点选择性修饰的优先化学伙伴。二烯。著名的例子包括免疫毒素和市售的基于马来酰亚胺的抗体-药物偶联物（ADC），例如Adcetris，它们用于癌症治疗。在这些研究小组取得成功的关键因素中，有几种可以通过荧光团，亲和标签，自旋标记和药效团进行N-官能化的马来酰亚胺，以及它们在选择性和动力学方面的独特反应性。但是，长期以来，马来酰亚胺共轭反应一直被认为是不可逆的，并且仅在最近才报道了关于其可逆性和对水解的稳定性的系统研究。这篇综述概述了生物共轭中马来酰亚胺的各种应用，强调了它们的优缺点，最近的策略正在克服这些优点和缺点。最后，利用马来酰亚胺的荧光猝灭能力来制备荧光探针，该荧光探针主要用于硫醇分析物的特异性检测。综述的最后部分讨论了所报告结构，其光物理特征及其相对效率的摘要。最近的策略正在克服这些问题。最后，利用马来酰亚胺的荧光猝灭能力来制备荧光探针，该荧光探针主要用于硫醇分析物的特异性检测。综述的最后部分讨论了所报告结构，其光物理特征及其相对效率的摘要。最近的策略正在克服这些问题。最后，利用马来酰亚胺的荧光猝灭能力来制备荧光探针，该荧光探针主要用于硫醇分析物的特异性检测。综述的最后部分讨论了所报告结构，其光物理特征及其相对效率的摘要。