AzGGK TFA is an unnatural amino acid. AzGGK TFA is site-specifically incorporated into proteins via genetic-code expansion. AzGGK TFA can be used as a site-specific probe for ubiquitylation and SUMOylation. AzGGK TFA is a click chemistry reagent, it contains an Azide group and can undergo copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing Alkyne groups. It can also undergo strain-promoted alkyne-azide cycloaddition (SPAAC) reactions with molecules containing DBCO or BCN groups[1].