A recoverable and thermoresponsive polymer-protein bioconjugate is synthesized and employed in the purification of protein with free sulfhydryl groups. Initiator with disulphide was modified on the cysteine residue of the target protein. Poly(N-isopropylacrylamide) exhibiting a lower critical solution temperature was grown from the protein. The resulting protein-polymer conjugate was successfully thermoprecipitated and separated from other proteins. The approach was demonstrated with bovine serum albumin with the recycling yield of 76.4%. Enzyme activity test with papain verified the reversible polymer modification protected protein under extreme environments without affecting the functionality of the protein. This study implies the favorable potential of chemo-selective enriching and purification of proteins.
Formation
of protein–polymer conjugates (PPCs) is critical
for many studies in chemical biology, biomedicine, and enzymatic catalysis.
Polymers with coordinated physicochemical properties confer synergistic
functions to PPCs that overcome the inherent limitation of proteins.
However, application of PPCs has been synthetically restricted by
the limited modification sites and polymer grafting method. Here,
we present a versatile strategy for site-selective PPC synthesis.
The initiator was specifically tethered to the preoxidized glycan
moieties through oxime chemistry. Polymer brushes were grown in situ
from the glycan by atom-transfer radical polymerization to generate
well-controlled PPCs. Notably, the modification is site-specific,
multivalent, and alterable depending on protein glycosylation. Additionally,
we demonstrated that the cytocompatible method enabled the growth
of polymer chains from the surface of living yeast cells. These results
verified a facile technology for surface modification of biomacromolecules
by desired polymers for various biomedical applications.
Capsid protein of
porcine circovirus type 2 (PCV2) is an ideal
subunit vaccine candidate for the postweaning multisystemic wasting
syndrome. In this study, mannan-mediated targeting of PCV2ΔCap42‑233 protein to antigen presenting cells (APCs) was investigated for
the development of PCV2 vaccine. Mannan was attached to PCV2ΔCap42‑233 protein via an acid sensitive Schiff base reaction. The mannosylated
protein was endowed with the capacity to target the mannose receptor
on APCs as well as the ability of controlled release of the antigen
in the acidic condition of the lysosome. Finally, the immune response
of mannosylated PCV2ΔCap42‑233 protein in
mice was evaluated. The mannosylated protein exhibited the ability
to stimulate humoral immune response and enhance the immunity. Thus,
acid-sensitive and APCs-targeting mannosylated PCV2ΔCap42‑233 protein represents a promising candidate for the potential commercial
application as an efficient vaccine against porcine circovirus.
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