Membrane protein extraction and purification using styrene–maleic acid (SMA) copolymer: effect of variations in polymer structure

Research output: Contribution to journalArticlepeer-review


  • Kerrie Morrison
  • Aneel Akram
  • Ashlyn Mathews
  • Zoeya Khan
  • Jaimin Patel
  • Chumin Zhou
  • David Hardy
  • Charles Moore-Kelly
  • Roshani Patel
  • Victor Obida
  • Massod-ul-hassan Javed
  • Nikola Chmel
  • Alice Rothnie

Colleges, School and Institutes


The use of styrene–maleic acid (SMA) copolymers to extract and purify transmembrane proteins, while retaining their native bilayer environment, overcomes many of the disadvantages associated with conventional detergent-based procedures. This approach has huge potential for the future of membrane protein structural and functional studies. In this investigation, we have systematically tested a range of commercially available SMA polymers, varying in both the ratio of styrene and maleic acid and in total size, for the ability to extract, purify and stabilise transmembrane proteins. Three different membrane proteins (BmrA, LeuT and ZipA), which vary in size and shape, were used. Our results show that several polymers, can be used to extract membrane proteins, comparably to conventional detergents. A styrene:maleic acid ratio of either 2:1 or 3:1, combined with a relatively small average molecular mass (7.5–10 kDa), is optimal for membrane extraction, and this appears to be independent of the protein size, shape or expression system. A subset of polymers were taken forward for purification, functional and stability tests. Following a one-step affinity purification, SMA 2000 was found to be the best choice for yield, purity and function. However, the other polymers offer subtle differences in size and sensitivity to divalent cations that may be useful for a variety of downstream applications.


Original languageEnglish
Pages (from-to)4349-4360
JournalBiochemical Journal
Issue number23
Early online date30 Sep 2016
Publication statusPublished - 25 Nov 2016