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The influence of poly(styrene-co-maleic acid) copolymer structure on the properties and self-assembly of SMALP nanodiscs

DOI: 10.1021/acs.biomac.7b01539 DOI Help

Authors: Stephen C. L. Hall (University of Birmingham) , Cecilia Tognoloni (University of Bath) , Gareth J. Price (University of Bath) , Bert Klumperman (Stellenbosch University) , Karen J. Edler (University of Bath) , Tim R. Dafforn (University of Birmingham) , Thomas Arnold (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biomacromolecules

State: Published (Approved)
Published: December 2017

Abstract: Polymer stabilized nanodiscs are self-assembled structures composed of a polymer belt that wraps around a segment of lipid bilayer, and as such are capable of encapsulating membrane proteins directly from the cell membrane. To date, most studies on these nanodiscs have used poly(styrene-co-maleic acid) (SMA) with the term SMA-lipid particles (SMALPs) coined to describe them. In this study, we have determined the physical and thermodynamic properties of such nanodiscs made with two different SMA copolymers. These include a widely used and commercially available statistical poly(styrene-co-maleic acid) copolymer (coSMA) and a RAFT-synthesized copolymer with narrow molecular weight distribution and alternating styrene and maleic acid groups with a polystyrene tail, (altSMA). We define phase diagrams for each polymer, and show that, regardless of polymer topological structure, self-assembly is driven by the free energy change associated with the polymers. We also show that nanodisc size is polymer dependent, but can be modified by varying polymer concentration. The thermal stability of each nanodisc type is similar and both can effectively solubilize proteins from the E. coli membrane. These data show the potential for the development of different SMA polymers with controllable properties to produce nanodiscs that can be optimized for specific applications and will enable more optimized and widespread use of the SMA-based nanodiscs in membrane protein research.

Journal Keywords: SMALP; phase diagram; phospholipid nanodisc self-assembly; membrane protein; solubilization

Subject Areas: Biology and Bio-materials

Technical Areas: