Proteins carry out a wide variety of catalytic, regulatory, signalling and structural functions in living systems. Following their assembly on ribosomes and throughout their lifetimes, most eukaryotic proteins are modified by post-translational modifications; small functional groups and complex biomolecules are conjugated to amino acid side chains or termini, and the protein backbone is cleaved, spliced or cyclized, to name just a few examples. These modifications modulate protein activity, structure, location and interactions, and, thereby, control many core biological processes. Aberrant post-translational modifications are markers of cellular stress or malfunction and are implicated in several diseases. Therefore, gaining an understanding of which proteins are modified, at which sites and the resulting biological consequences is an important but complex challenge requiring interdisciplinary approaches. One of the key challenges is accessing precisely modified proteins to assign functional consequences to specific modifications. Chemical biologists have developed a versatile set of tools for accessing specifically modified proteins by applying robust chemistries to biological molecules and developing strategies for synthesizing and ligating proteins. This Review provides an overview of these tools, with selected recent examples of how they have been applied to decipher the roles of a variety of protein post-translational modifications. Relative advantages and disadvantages of each of the techniques are discussed, highlighting examples where they are used in combination and have the potential to address new frontiers in understanding complex biological processes.

蛋白质在生命系统中发挥着广泛的催化、调节、信号和结构功能。在它们在核糖体上组装后并在其整个生命周期中，大多数真核蛋白质都会通过翻译后修饰进行修饰；小官能团和复杂的生物分子与氨基酸侧链或末端结合，蛋白质主链被切割、剪接或环化，仅举几个例子。这些修饰调节蛋白质活性、结构、位置和相互作用，从而控制许多核心生物过程。异常的翻译后修饰是细胞应激或功能障碍的标志，并与多种疾病有关。因此，了解哪些蛋白质被修饰，在哪些地点以及由此产生的生物学后果是一个重要但复杂的挑战，需要跨学科方法。关键挑战之一是获取精确修饰的蛋白质以将功能结果分配给特定修饰。化学生物学家开发了一套多功能工具，通过将稳健的化学应用于生物分子并开发合成和连接蛋白质的策略，来获取经过特殊修饰的蛋白质。本综述概述了这些工具，并选择了最近的示例来说明它们如何应用于破译各种蛋白质翻译后修饰的作用。讨论了每种技术的相对优点和缺点，