Three‐in‐One Chromatography‐Free Purification, Tag Removal, and Site‐Specific Modification of Recombinant Fusion Proteins Using Sortase A and Elastin‐like Polypeptides

Applied in tandem, elastin-like polypeptides (ELPs) and the sortase A (SrtA) transpeptidase from Staphylococcus aureus provide a general method for chromatography-free purification of tag-free recombinant proteins and optional, site-specific and homogeneous conjugation of the protein to a small molecule. This system provides an efficient, practical mechanism for generating bioactive proteins and protein-small-molecule combination therapeutics at high yields and purities.