Using a mutant of ubiquitin with a C-terminal cysteine residue and a poly-histidine tag with TEV recognition sequence, novel ABC triblock copolymers were constructed with protein as the “B” block. The N-terminus and lysine residues were modified by the activated ester of an ATRP initiator (EBIB). Then, grafting-from was performed using photo-ICAR-ATRP, with 50ppm copper catalyst and 1% photoinitiator loading, and monomer at 2wt%, under blue light. Then, the cysteine at the C-terminus was targeted by Thiol-Michael reaction of the -SH group with a maleimide-functionalized chain transfer agent (PAETC). Grafting-from was performed using photo-RAFT, with 5wt% monomer and 0.66% photoinitiator at low (1mg/ml) protein concentration. Sequence analysis confirms selective targeting of the N-terminus. Circular dichroism was performed to assess protein stabilization afforded by these modifications. Proteins with two, unique, directly and covalently attached polymers present another step towards multifunctional bioconjugates.

Using orthogonal grafting-from strategies to access well-defined 2-polymer, 1-protein bioconjugates

2019 Spring National Meeting

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