Regioselective Cysteine Bioconjugation by Appending a Labeled Cystein Tag to a Protein by Using Protein Splicing in trans

Orthogonal cysteines: The chemical modification of cysteine residues is one of the most important methods for the chemoselective bioconjugation of proteins; however, it lacks regioselectivity. By assembling the protein from two pieces using protein trans-splicing, regioselectivity can be achieved. This reaction can even be performed in complex mixtures such as cell extracts.