Acid-Labile Traceless
Click Linker for Protein Transduction
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Abstract
Intracellular delivery of active proteins presents an
interesting
approach in research and therapy. We created a protein transduction
shuttle based on a new traceless click linker that combines the advantages
of click reactions with implementation of reversible pH-sensitive
bonds. The azidomethyl-methylmaleic anhydride (AzMMMan) linker was
found compatible with different click chemistries, demonstrated in
bioreversible protein modification with dyes, polyethylene glycol,
or a transduction carrier. Linkages were stable at physiological pH
but reversible at the mild acidic pH of endosomes or lysosomes. We
show that pH-reversible attachment of a defined endosome-destabilizing
three-arm oligo(ethane amino)amide carrier generates an effective
shuttle for protein delivery. The cargo protein nlsEGFP, when coupled
via the traceless AzMMMan linker, experiences efficient cellular uptake
and endosomal escape into the cytosol, followed by import into the
nucleus. In contrast, irreversible linkage to the same shuttle hampers
nuclear delivery of nlsEGFP which after uptake remains trapped in
the cytosol. Successful intracellular delivery of bioactive ß-galactosidase
as a model enzyme was also demonstrated using the pH-controlled shuttle
system