Photo-induced polymerization of styrene-maleic acid copolymers for the extraction of membrane proteins

Abstract

We report herein the photoinduced electron/energy transfer–reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of styrene-maleic anhydride (SMAnh) using the photocatalyst, zinc tetraphenylporphirine, under a white cool LED light. PET-RAFT is an easy and convenient polymerization method that does not require deoxygenation unlike other radical polymerizations. Various parameters, for example, the amount of styrene in the feed or the solvent, and their influence on the polymerization were studied. After hydrolysis of the anhydride moieties, the resulting styrene-maleic acid (SMA) copolymers obtained by PET-RAFT copolymerization were evaluated for their solubilization efficiency of three different membrane proteins, BmrA and AcrB, overexpressed in Escherichia coli, and A_2AR, expressed in insect cells (Sf9). The different copolymers provided similar solubilization rates to the commercially available SMA; however, a highly improved migration behavior on sodium dodecyl-sulfate polyacrylamide gel electrophoresis was observed which could, facilitate downstream analyses. Overall, we demonstrated that PET-RAFT is a versatile oxygen tolerant polymerization technique to yield SMA, a suitable polymer for biochemical applications.