MeO-PEG-alkyne (MW 750Da) is a click chemistry reagent that includes an alkyne group. It possesses an azide group, allowing for copper-catalyzed azide-alkyne cycloaddition (CuAAc) with alkyne-containing molecules. Additionally, it can undergo strain-promoted azide-alkyne cycloaddition (SPAAC) with molecules containing DBCO or BCN groups.