Post-translational modifications (PTMs) greatly expand the structures and functions of proteins in nature1,2. Although synthetic protein functionalization strategies allow mimicry of PTMs3,4, as well as formation of unnatural protein variants with diverse potential functions, including drug carrying5, tracking, imaging6 and partner crosslinking7, the range of functional groups that can be introduced remains limited. Here we describe the visible-light-driven installation of side chains at dehydroalanine residues in proteins through the formation of carbon-centred radicals that allow C-C bond formation in water. Control of the reaction redox allows site-selective modification with good conversions and reduced protein damage. In situ generation of boronic acid catechol ester derivatives generates RH2C• radicals that form the native (β-CH2-γ-CH2) linkage of natural residues and PTMs, whereas in situ potentiation of pyridylsulfonyl derivatives by Fe(II) generates RF2C• radicals that form equivalent β-CH2-γ-CF2 linkages bearing difluoromethylene labels. These reactions are chemically tolerant and incorporate a wide range of functionalities (more than 50 unique residues/side chains) into diverse protein scaffolds and sites. Initiation can be applied chemoselectively in the presence of sensitive groups in the radical precursors, enabling installation of previously incompatible side chains. The resulting protein function and reactivity are used to install radical precursors for homolytic on-protein radical generation; to study enzyme function with natural, unnatural and CF2-labelled post-translationally modified protein substrates via simultaneous sensing of both chemo- and stereoselectivity; and to create generalized 'alkylator proteins' with a spectrum of heterolytic covalent-bond-forming activity (that is, reacting diversely with small molecules at one extreme or selectively with protein targets through good mimicry at the other). Post-translational access to such reactions and chemical groups on proteins could be useful in both revealing and creating protein function.

中文翻译：

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活性蛋白侧链的光驱动翻译后安装

翻译后修饰 (PTM) 极大地扩展了自然界中蛋白质的结构和功能1,2。尽管合成蛋白质功能化策略允许模拟 PTMs3,4，以及形成具有多种潜在功能的非天然蛋白质变体，包括载药 5、跟踪、成像 6 和伴侣交联 7，但可以引入的功能组范围仍然有限。在这里，我们描述了通过形成以碳为中心的自由基，从而允许在水中形成 CC 键，在蛋白质中脱氢丙氨酸残基处的可见光驱动侧链安装。对反应氧化还原的控制允许具有良好转化率和减少蛋白质损伤的位点选择性修饰。硼酸儿茶酚酯衍生物的原位生成产生 RH2C• 自由基，形成天然残基和 PTM 的天然 (β-CH2-γ-CH2) 键，而 Fe(II) 对吡啶磺酰基衍生物的原位增强作用生成 RF2C• 自由基形成带有二氟亚甲基标记的等效 β-CH2-γ-CF2 键。这些反应具有化学耐受性，并将广泛的功能（超过 50 个独特的残基/侧链）整合到不同的蛋白质支架和位点中。在自由基前体中存在敏感基团的情况下，可以化学选择性地应用引发，从而能够安装以前不相容的侧链。产生的蛋白质功能和反应性用于安装自由基前体，以产生均裂的蛋白质自由基；用天然的方法研究酶的功能，通过同时检测化学选择性和立体选择性，非天然和 CF2 标记的翻译后修饰的蛋白质底物；并创建具有一系列异解共价键形成活性的广义“烷化剂蛋白质”（即，在一个极端与小分子发生不同的反应，或在另一个极端通过良好的模仿与蛋白质目标选择性地发生反应）。对蛋白质上的此类反应和化学基团的翻译后访问可用于揭示和创建蛋白质功能。在一个极端与小分子发生不同的反应，或者在另一个极端通过良好的模仿选择性地与蛋白质靶标发生反应）。对蛋白质上的此类反应和化学基团的翻译后访问可用于揭示和创建蛋白质功能。在一个极端与小分子发生不同的反应，或者在另一个极端通过良好的模仿选择性地与蛋白质靶标发生反应）。对蛋白质上的此类反应和化学基团的翻译后访问可用于揭示和创建蛋白质功能。