Bifunctional pyridoxal derivatives as efficient bioorthogonal reagents for biomacromolecule modifications.

Two types of pyridoxal analogs, azido pyridoxal (PL-N3) and carboxyl pyridoxal (PL-COOH), were developed as novel bifunctional bioorthogonal molecules. These molecules showed fast imine formation with hydrazinyl groups and stable covalent linkages via azido/carboxyl groups, and thus were of great use for site-specific peptide and protein modifications.