SMA is short for styrene maleic anhydride. It belongs to a group of synthetic polymers that can form synthetic nanodiscs. These are small-disc-shaped complexes that consist of the polymer, phospholipids of the cell membrane and a membrane protein. They find use in life sciences and medicine for membrane protein stabilization & solubilization without the use of detergents. Another synthetic polymer that can be used for the same reason is
DIBMA. Both Cube Biotech and Orbiscope sell the same polymeric SMA backbone for SMALP. We customized SMALP to make it more convenient to use within biotechnological research. Orbiscope sells a 20 percent solid content SMALP viscous solution in water, while our products are easy to handle powders.
We add HEPES and NaCl to the SMALP products and freeze-dry them to create a ready-to-use powder that guarantees a stable pH of 7.5. It has been shown that some SMALP’s do not work at low pH (1). These additional steps result in a sodium counter ion in our SMALP products, in contrast to Orbiscope’s potassium counter ion.
The product from Cube Biotech can be directly used for your experiments.
Fig. 1: All of our SMALP products come as lyophilized powder. Just add water and you obtain your SMALP product buffered at pH 7.5 in HEPES.
Fig. 2: Schematic depiction of SMA (red) while solubilizing a membrane protein (orange). The Phospholipids (grey) originate from the cell membrane and are therefore the native lipid environment of the membrane protein.
SMA Products
All SMAs are delivered as lyophilized powder.
Features - Our Individual SMAs in comparison
| Feature | SMALP
140 | SMALP
140-I | SMALP
200 | SMALP
300 | SMALP
502-E |
| Polymer styrene-to-maleic-anhydride ratio [n:m] | 1.4:1 | 1.4:1 | 2:1 | 3:1 | 1.5:1 |
| Molecular weight | 5,000 Da | 5,000 Da | 6,500 Da | 10,000 Da | 7,000 Da |
| Form | Lyophilized powder | Lyophilized powder | Lyophilized powder | Lyophilized powder | Lyophilized powder |
| pH, after solving | 7.5 | 7.5 | 7.5 | 7.5 | 8.0 |
| Divalent cationic tolerance | < 5 mM | < 100 mM | < 5 mM | < 5 mM | < 4 mM |
| Color | Amber | Brownish | Yellowish | Colorless | Yellow |
| Odor | Odorless | Odorless | Odorless | Odorless | Odorless |
| Other noteworthy feature | | is imidized with DMAPA | Most commonly used SMA | | Newest SMA - increase solubilization rate |
In case you have further questions about our SMA products, feel free to contact us via "
[email protected]"
Frequently asked questions - FAQ
| What SMA is the best one to use? |
| This is a tricky question, as it depends on the membrane protein which SMA performs best, however SMA 30010S is in general the most recommended. Keep in mind that this is no guarantee for it to be the best but in our experience, it is a good allrounder. |
| What are the recommended concentrations of SMA? |
| Mix the supplied solutions at a concentration of 1-5% SMALP to the total solution. These conditions can be used as indications. The optimal SMA concentration must be determined separately for each experiment. |
| How is SMA stored? |
| Store at cool and dry places, protected from direct sunlight. Long-term storage is recommended at 4°C |
| The viscosity of my SMA has decreased, what happened? |
| This can occur by storing SMA at low temperatures (as recommended!). Simply warm the SMA solution up to room temperature to restore its original viscosity. |
| How do I quantify the amount of protein after SMA treatment? |
In contrast to DIBMA, SMA absorbs light at 280 nm similar to proteins. Therefore ultraviolet absorption is no option here. However other protein quantification assays are viable options like: - Bicinchoninic Acid (BCA)
- Bradford
- Folin-Lowry in some cases
|
SMA products by Cube Biotech were used in the following publications:
Disclaimer
References
- Hall, Stephen CL, et al. "An acid-compatible co-polymer for the solubilization of membranes and proteins into lipid bilayer-containing nanoparticles." Nanoscale 10.22 (2018): 10609-10619.
- Overduin, M. et al. (2021) "Structures and Dynamics of Native-State Transmembrane Protein Targets and Bound Lipids". Membranes, 11, 451. https://doi.org/10.3390/membranes11060451
Fig. 2: Schematic depiction of SMA (red) while solubilizing a membrane protein (orange). The Phospholipids (grey) originate from the cell membrane and are therefore the native lipid environment of the membrane protein.
