[Development and Application of Catalytic Tyrosine Chemical Modification]

The chemical labeling of proteins with synthetic small compounds is a key technique in chemical biology, protein-based therapy, and material science. Much of the chemical labeling of native proteins, however, depends on the labeling of lysine and cysteine residues. While those methods have contributed significantly to native protein labeling, alternative methods that can modify different amino acid residues are still required. Here we report the development of a novel methodology of oxidative tyrosine labeling, which was inspired by the single-electron transfer reaction in biological systems. The tyrosine labeling methods were developed using small compounds such as N-methyl luminol derivative, N'-acyl-N,N-phenylenediamine, and 1-methyl-4-aryl-urazole under labeling conditions using a hemin, peroxidase, or ruthenium photocatalyst. These methods were applied to target- and site-selective protein modification.