Synthesis of Zwitterionic Polymers Containing Tertiary Sulfonium Group for Protein Stabilization.

Research paper by Ryutaro R Imamura, Hideharu H Mori

Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: Biomacromolecules


The present study demonstrates the controlled synthesis and biological potential of poly(N-acryloyl-L-methionine methyl sulfonium salt)s (poly(A-Met(S+)-OH)s), which mimic dimethylsulfoniopropionate (DMSP), a compound produced by marine algae to protect their proteins. The novel sulfonium-containing zwitterionic polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the amino acid-based monomer N-acryloyl-L-methionine (A-Met-OH) followed by a post-modification process in which the sulfide groups were reacted with iodomethane. The DMSP-mimic zwitterionic macromolecules were shown for the first time to exhibit low cytotoxicity and the ability to stabilize proteins. By adding the resulting poly(A-Met(S+)-OH)s to horse radish peroxidase (HRP) solution, the activity of HRP was maintained even after storage at 4 °C for several days. In addition, the protein activities were tested using peroxidase-labeled antibody to mouse immunoglobulin G (IgG-HRP) and alkaline phosphatase (ALP) after storage and for HRP after freeze-thaw cycles. Amphiphilic random copolymers, poly(A-Met(S+)-OH-co-BA)s, also exhibited excellent properties for protein stabilization.