Product Description: DBCO-N-bis(PEG4-NHS ester) is a PEG linker which contains two PEG4-NHS ester and a DBCO group. DBCO-N-bis(PEG4-NHS ester) is useful for protein modification or labeling. DBCO-N-bis(PEG4-NHS ester) is a click chemistry reagent, it contains a DBCO group that can undergo strain-promoted alkyne-azide cycloaddition (SPAAC) with molecules containing Azide groups.