Biophysical characterization of a series of novel non‐RAFT copolymers with improved buffer behavior

Abstract

Synthetic amphipathic polymers present an invaluable tool for excision and liberation of superstructures of membrane proteins (MPs) and their surrounding annular membrane bilayer in donut‐shaped nanoparticles or discs. Styrene‐co‐maleic acid polymers (SMAs) have demonstrated most efficiency for the structural characterization of membrane proteins. However, some drawbacks such as sensitivity to acidic pH and high concentration of divalent cations, interference with the spectroscopic profiles of proteins, high polydispersity index (PDI) and nonspecific interaction with protein surface have hindered the ultimate optimal utilization of SMA polymers for functional characterization of MPs in lipid bilayer and hence for drug discovery purposes. We have developed multiple series of novel non‐RAFT amphipathic polymers that demonstrate improved behaviors in acidic pH and high concentration of calcium. Some of these unique amphipathic polymers display exemplary polydispersity (PDI ~1), strict alternation (a well‐defined sequence of comonomers) and distinct spectrophotometric profiles. We further characterized the application of these novel polymeric detergents for purification of a model integral beta‐barrel MP, PagP, from the outer membrane of E. coli.