ChemBioChem, 2016, doi: 10.1002/cbic.201600254
Kodal A L B, Rosen C B, Mortensen M R, Tørring T, Gothelf K V.
Department of Chemistry and iNANO, Center for DNA Nanotechnology, Aarhus University, Aarhus 8000, Denmark
Many medical and biotechnological applications rely on labeling of proteins, but one key challenge is the production of homogeneous and site-specific conjugates. This can rarely be achieved by mere residue-specific random labeling, but requires genetic engineering. Using site-selective DNA-templated reductive amination we create DNA-protein conjugates with control over labeling stoichiometry without genetic engineering. A guiding DNA strand with a metal-binding functionality facilitates site-selectivity by directing coupling of a second reactive DNA strand to the vicinity of a protein metal-binding site. Here, we demonstrate DNA-templated reductive amination for His6-tagged proteins and native metal-binding proteins, including IgG1 antibodies. We also use a cleavable linker between the DNA and the protein to remove the DNA and introduce a single aldehyde to proteins. This functions as a handle for further modifications with desired labels. In addition to directing the aldehyde positioning, the DNA provides a straightforward route of purification between reaction steps.