6-Azido-L-lysine hydrochloride

The in vivo incorporation of clickable unnatural amino acids such as 6-Azido-L-lysine with unique reactivity at a defined postition is used for functionalization of proteins. The azide functionalities in the protein can then be modified with almost any alkyne bearing molecule by Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Copper-free alternatives with strained internal alkynes are also available (SPAAC). Some examples enabled with this technique are protein PEGylation, masking with sugars, and the attachment to antibodies.