Commercial SMA Polymers

The discovery that copolymers composed of styrene and maleic acid groups can solubilize native lipid:protein complexes direct from cells or raw membrane has stimulated a flurry of new research.

SMA producer Polyscope Polymers from the Netherlands is an official sponsor of the SMALP network and is providing the community three types of SMA products for membrane protein solubilization. These have been widely used and are recommended to test and optimize purification of membrane proteins along with bound lipids and partner proteins. A ratio of styrene to maleic acid of around around 2:1 is generally most recommended.

Product S:MA Ratio† Mw† (g/mole) Mn† (g/mole) Source
Xiran® SL 25010 P20 3:1 10000 4000 Polyscope
Xiran® SL 30010 P20 2.3:1 6500 2500 Polyscope
Xiran® SL 40005 P20 1.2:1 5000 2000 Polyscope

Contact us for samples of XIRAN® SL 25010 P20, SL 30010 P20 and SL 40005 P20 reagents for collaborative research, as these have now been formulated as an activated set for convenient use. The samples are provided as ready-to-use solutions for membrane solubilization. Detailed product information will be provided in the enclosed certificate of analysis (CoA).

Other SMA polymers are commercially available too, and are listed below.

Product S:MA Ratio† Mw† (g/mole) Mn† (g/mole) Source
SMA 2:1 2:1 10100 n/a Profoldin
SMA 3:1 3:1 7800 n/a Profoldin
SMA2000 2:1 7500 3000 Cray Valley
SMA3000 3:1 9500 3800 Cray Valley
Lipodisq L8920 2:1 n/a n/a Sigma
Lipodisq L9045 3:1 n/a n/a Sigma
Lipodisq L9170 3:1 n/a n/a Sigma

† The SMA copolymers are defined by the average ratio of styrene to maleic acid repeat units (S:MA). The lengths and blockiness of the polymers is different for each. The number average molecular weight (Mn) is total weight of the polymer molecules divided by the number of molecules. The weight average molecular weight (Mw) is more sensitive to the larger chains present. The polydispersity index (PDI) equals Mw/Mn and is a measure of distribution of the molecular weights.

Commercial non-SMA polymers that form discs

In addition to SMA polymers, related synthetic copolymers convert membranes into discs and are listed below.

Product S:MA Ratio† Mw† (g/mole) Mn† (g/mole) Source
DIBMA n/a 15300 8400 Anatrace
PMA n/a n/a n/a Avanti
Sokalan CP9 n/a 15300 8400 BASF

¶ PMA refers to polymethacrylate copolymer product "N−C4−52−6.9" from Avanti. This belongs to the family of polymers referred to in Yasuhara K, Arakida J, Ravula T, Ramadugu SK, Sahoo B, Kikuchi JI, Ramamoorthy A. 2017. Spontaneous Lipid Nanodisc Fomation by Amphiphilic Polymethacrylate Copolymers. J Am Chem Soc. 139(51):18657-18663.

Anatrace launched their version of purified DIBMA in September 2018 based upon the work of Sandro Keller and is looking forward to developing and launching additional polymers in 2019. Sokalan CP9 is the tradename of an alternating copolymer of maleic acid and diisobutylene (2,4,4-trimethylpent-1-ene) (DIBMA). Sandro Keller's slides and the 2016 paper by AO Oluwole et. al. on DIBMA show that it is well-suited to solubilizing larger membrane proteins. It is also compatible with UV and CD experiments and higher levels of divalent cations such as calcium and magnesium.

We welcome you to discuss your thoughts on SMA and related polymers below or by contacting us.