The process of forming fluorophore by bioorthogonal reactions of tetrazine [5]

The process of forming fluorophore by bioorthogonal reactions of tetrazine [5]Tetrazine ligation is a class of bioorthogonal reactions, which is the reaction of dienophile and S-tetrazine in the inverse electron demand Diels-Alder (IEDDA) reaction. Tetrazine ligation is a method of biological combination that can react quickly without catalysis. Tetrazine ligation is a rapid reaction with a second-order rate constant of 2000 M^-1•S^-1 (9:1 methanol/water), which allows modification of biomolecules at very low concentrations. This reaction can proceed at very high speeds in aqueous media. The reaction was also carried out in aqueous medium using trans-cyclooctene (TCO) or norbornene as a dienophile at a secondary rate of 1 M^-1•S^-1. Tetrazine ligation has been applied to label living cells and other biological entities,chemistry, biomedicine and other fields.Applications of Tetrazine LigationTetrazine ligation can be used to rapidly construct radionuclide-labeled probes, which have been applied to label living cells and other biological entities. For example, Devaraj Neal K. reported that photoactivated tetrazine achieves accurate bioorthogonal chemistry of living cells.^[1] Bioorthogonal cycloaddition reactions between tetrazines and strain dienophiles are widely used for labeling proteins, lipids, and glycans because of their extremely rapid kinetics. However, controlling such chemical reactions with a high degree of spatial and temporal precision in living mammalian cells remains a challenge. In this research work, the researchers demonstrated a versatile photoactivation method to form tetra-nitrogen by trapping dihydrotetra-nitrogen with light. Photocuring (dihydrotetra-nitrogen is trapped by light), followed by spontaneous conversion to active tetrazine, bioorthogonal cycloaddition reactions with dienophile substances such as TCO can be rapidly completed in living cells.