Fluorogenic Protein Labeling by Generation of Fluorescent Quinoliziniums Using [Cp*RhCl 2 ] 2 .

Fluorogenic labeling has received considerable attention as a result of the high demand in chemical biology and synthetic biology applications. Herein, we develop a new strategy for fluorescent turn-on ligation targeting alkyne- and quinoline-linked peptides and proteins (λ em of 515 nm and up to Φ F of 0.20) using the [Cp*RhCl 2 ] 2 catalyst. The good conversion, high flexibility, broad utility, ease of use, and mild reaction conditions are great advantages to extend the rhodium-mediated turn-on fluorogenic bioconjugation for further applications.