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


  • We are grateful to S. Brenzel for construction of plasmid pSB34 and C. Ludwig for construction of plasmid pCL39. We thank U. Linne for help with mass spectrometry and M. Marahiel for support. We thank F. Bernhard for providing plasmid pAT37. Funding was provided by the DFG (Emmy Noether program) and the Fonds der Chemischen Industrie.


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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.