An ex situ gaseous reagent for multicomponent amine bioconjugation

Bioconjugation is a large field with many diverse goals, needs, and challenges, that requires a broad toolbox of fundamentally different synthetic approaches. As nucleophilic groups are prevalent in biomolecules, the ability to crosslink two nucleophilic sites offers an attractive approach to construct useful bioconjugates. New technologies for crosslinking with gaseous reagents and with minimal perturbation of natural structure could provide new ways to think about bioconjugation in complex environments. We report a minimalist gaseous sulfonyl chloride-derived reagent for multicomponent bioconjugation with amine, phenol, or aniline reagents to afford urea or carbamate products. In utilizing a gas-phase reagent for a reaction mediated by metal ions, a variety of biologically relevant molecules such as saccharide, PEG, fluorophore, and affinity tag can be efficiently crosslinked to the N-terminus or lysine side chain amines on natural polypeptides or proteins. The application of this method to the production of functional, modified proteins was demonstrated by fluorescence imaging of a cancer cell line and by the facile preparation of a peptide–protein conjugate.