N- (TCO) -N-bis (PEG4-acid)

N- (TCO) -N-bis (PEG4-acid) is a branched click chemistry reagent with a terminal TCO group and two terminal carboxylic acids. This reagent can react with tetrazine-containing molecule to form a stable covalent bond . The inverse-electron demand Diels-Alder cycloaddition reaction of TCO with tetrazines is the fastest bioorthogonal reaction with exceptional selectivity. The terminal carboxylic acids can react with primary amino groups in the presence of activators (e.g. EDC, HATU) .