Bottlebrush polymeric structures have long intrigued polymer chemists since they possess unique properties compared to their linear counterparts. Natural bottlebrush polymers such as proteoglycans and mucin glycoproteins consist of polypeptide backbones with linear or branched polysaccharide side chains and play important roles in cell-surface biology. We have developed a new route to synthesize the first glycosylated bottlebrush copolypeptide mimics of these native glyco-brush polymers. Polymerization of α-amino acid N-carboxyanhydrides (NCAs) in a tandem organometallic catalysis method and a “grafting-from” approach gave brush glycopolypeptides with tunable physical properties. A non-canonical activatable amino acid NCA was used to form the polypeptide backbone and variable side chain densities (25%-100%) were achieved through copolymerization of the backbone NCA with a canonical NCA. Both backbone and side-chain degrees of polymerization could easily be tuned via the monomer to initiator ratios. We studied the side-chain growth kinetics of various glycosylated structures using attenuated total reflectance Fourier transform infrared spectroscopy. Second order kinetic parameters were determined for each glycosylated amino acid NCA at varied densities. Our results indicate drastically different kinetics depending on the side-chain conformation. In summary, we demonstrated an efficient facile method for producing the first glycosylated bottlebrush copolypeptides with tunable side-chain densities and conformations. These structures are expected to be excellent mimics of natural glycosylated brush proteins.

Glycosylated polypeptide bottlebrushes

2019 Fall National Meeting

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