posted on 2016-02-11, 00:00authored byMelissa Lucius, Rebecca Falatach, Cameron McGlone, Katherine Makaroff, Alex Danielson, Cameron Williams, Jay C. Nix, Dominik Konkolewicz, Richard C. Page, Jason A. Berberich
Polymers
are often conjugated to proteins to improve stability;
however, the impact of polymer chain length and functional groups
on protein structure and function is not well understood. Here we
use RAFT polymerization to grow polymers of different lengths and
functionality from a short acrylamide oligomer with a RAFT end group
conjugated to lysozyme. We show by X-ray crystallography that enzyme
structure is minimally impacted by modification with the RAFT end
group. Significant activity toward the negatively charged Micrococcus lysodeicticus cell wall was maintained when
lysozyme was modified with cationic polymers. Thermal and chemical
stability of the conjugates was characterized using differential scanning
fluorimetry and tryptophan fluorescence. All conjugates had a lower
melting temperature; however, conjugates containing ionic or substrate
mimicking polymers were more resistant to denaturation by guanidine
hydrochloride. Our results demonstrate that tailoring polymer functionality
can improve conjugate activity and minimize enzymatic inactivation
by denaturants.