The affinity tags are unique proteins/peptides that are attached at the N- or C-terminus of the recombinant proteins. These tags help in protein purification. Additionally, some affinity tags also serve a dual purpose as solubility enhancers for challenging protein targets. By applying a combinatorial approach, carefully chosen affinity tags designed in tandem have proven to be very successful in the purification of single proteins or multi-protein complexes. In this mini-review, the key features of the most commonly used affinity tags are discussed. The affinity tags have been classified into two significant categories, epitope tags, and protein/domain tags. The epitope tags are generally small peptides with high affinity towards a chromatography resin. The protein/domain tags often perform double duty as solubility enhancers as well as aid in affinity purification. Finally, protease-based affinity tag removal strategies after purification are discussed.

亲和标签是独特的蛋白质/肽，附着在重组蛋白质的N或C末端。这些标签有助于蛋白质纯化。另外，一些亲和标签还具有双重用途，作为挑战性蛋白质靶标的溶解度增强剂。通过应用组合方法，精心设计的串联亲和标签在单蛋白或多蛋白复合物的纯化中已被证明非常成功。在此迷你审查中，讨论了最常用的亲和标签的关键功能。亲和标签已分为两大类，抗原决定簇标签和蛋白质/结构域标签。表位标签通常是对色谱树脂具有高亲和力的小肽。蛋白质/结构域标签通常起着溶解性增强剂的双重作用，并有助于亲和纯化。最后，讨论了纯化后基于蛋白酶的亲和标签去除策略。