Site-Specific Bioconjugation through Enzyme-Catalyzed Tyrosine-Cysteine Bond Formation

ACS Cent Sci. 2020 Sep 23;6(9):1564-1571. doi: 10.1021/acscentsci.0c00940. Epub 2020 Aug 21.


The synthesis of protein-protein and protein-peptide conjugates is an important capability for producing vaccines, immunotherapeutics, and targeted delivery agents. Herein we show that the enzyme tyrosinase is capable of oxidizing exposed tyrosine residues into o-quinones that react rapidly with cysteine residues on target proteins. This coupling reaction occurs under mild aerobic conditions and has the rare ability to join full-size proteins in under 2 h. The utility of the approach is demonstrated for the attachment of cationic peptides to enhance the cellular delivery of CRISPR-Cas9 20-fold and for the coupling of reporter proteins to a cancer-targeting antibody fragment without loss of its cell-specific binding ability. The broad applicability of this technique provides a new building block approach for the synthesis of protein chimeras.