Rapid, Stoichiometric, Site-Specific Modification of Aldehyde-Containing Proteins Using a Tandem Knoevenagel-Intra Michael Addition Reaction.

A site-specific modification of aldehyde-containing proteins using a tandem Knoevenagel-intra Michael addition reaction was developed. The reaction featured fast kinetics (50 M-1 s-1 ) and favorable stoichiometry. Various functionalities could be introduced into the protein with little impact on its function and conformation. The reaction was successfully applied in the labeling of living cells.