MAASTY exists as a product for an unglamorous reason. We kept getting good preps with it, we kept giving it away, and the material transfer agreements were making everyone miserable. Selling it was how we stopped doing paperwork and got back to work.
Across our own benches and our collaborators', a disproportionate number of the preps that worked first time were preps that used this polymer. Not a marginal improvement in a benchmark. Targets that had been difficult behaving, and difficult samples surviving all the way to a grid.
The clearest case was human TRPM4. We solubilised it directly from mammalian membranes into MAASTY nanodiscs and it went to 3.5 Å by single-particle cryo-EM, with a Ca2+ ion resolved in its binding site and endogenous cholesterol still bound, without extensive reconstitution optimisation. The same protein, in the same lab, prepared in AASTY nanodiscs gave a lower-resolution structure.
So we sent it to people who asked. And every single time, the material transfer agreement. Weeks of legal review at two institutions, occasionally months, to move a few hundred milligrams of a polymer that is not expensive for us to make. The cost was never the polymer. The cost was two research offices negotiating terms over a vial while someone with a protein and a booked microscope slot waited.
Selling it removes the MTA. We are deleting the paperwork that stood between it and the people who wanted to use it.
All of the following is published in Nature Communications 2025. Nothing on this page is unpublished or unreviewed.
Human TRPM4 extracted directly from mammalian membranes in MAASTY50 and refined with C4 symmetry to 3.5 Å overall resolution. No detergent step, no re-lipidation, no lengthy optimisation of the nanodisc system before it produced a usable map.
The same protein prepared in AASTY nanodiscs in the same lab gave a lower-resolution structure. We attribute this to less co-purified phosphatidylinositol and other charged lipids in the AASTY sample, and the conformational heterogeneity that followed. This is the one true side-by-side comparison we have, and it favours MAASTY.
Cholesterol confirmed by MALDI-TOF and two molecules modelled in sites previously annotated as cholesteryl hemisuccinate sites. Lipidomics found PI, PC, PE, PG and PS species, with phosphatidylinositol enriched far above the 1 to 2% typical of plasma membrane.
A Ca2+ ion resolved in the established binding site, coordinated by Glu828, Gln831, Asn865 and Asp868. Capturing a cation-bound state in a polyanionic copolymer is not something we took for granted, and it opens divalent-dependent targets to this approach.
Effective solubilisation of monomeric rSERCA1a, homodimeric hKCNK18, homotrimeric cASIC1 and tetrameric hTRPM4 from mammalian membranes, across a range of lipid compositions and charge states.
Made by RAFT with a defined number-average molecular weight of 7.0 to 8.2 kDa and a controlled composition drift, so a batch in two years should behave like a batch today. Commercial SMA is a polydisperse industrial hydrolysate with reported batch-to-batch variation.
Two cases where we are not the right answer, stated up front so you do not waste a month finding out.
DIBMA has no aromatic monomer and is UV transparent. MAASTY is styrenic, so it absorbs where your protein absorbs, exactly as SMA does. If clean UV quantification or CD is central to your workflow, do not work around it, use a polymer that does not have the problem.
If you need to work well below pH 7, note that zwitterionic and quaternary-ammonium SMA derivatives are reported to tolerate low pH where parent SMA precipitates. Within our series MAASTY60 has the lowest pKa at 7.44 and is the variant to try first, but MAASTY is not a low-pH polymer.
Values for SMA and DIBMA are taken from the published literature rather than from our own side-by-side experiments, and are marked as reported. The AASTY and MAASTY figures are ours.
| Property | SMA | DIBMA | AASTY | MAASTY |
|---|---|---|---|---|
| Hydrophobic monomer | Styrene | Diisobutylene | Styrene | Styrene |
| Synthesis | Industrial radical | Industrial radical | RAFT | RAFT |
| Composition tunable | Limited grades | Limited grades | Yes, narrow window | Yes, five variants, pKa 7.44–8.23 |
| High-resolution structure demonstrated | Yes | Reported, fewer | Yes, lower resolution on hTRPM4 | Yes, 3.5 Å on hTRPM4 |
| UV transparent at 280 nm | No | Yes | No | No |
| Divalent cations | Reported highly sensitive | Reported more tolerant than SMA | Chelates | Chelates more strongly than AASTY; higher-MAA variants tolerate best during disc formation |
Composition sets the pKa, the pKa sets the charge state in your buffer, and the charge state decides whether your target comes out. In our hands the best variant moved across the series depending on the protein, and the differences were not subtle: MAASTY40 and MAASTY45 were the most effective for rSERCA1a, with efficiency falling as MAA content rose, while the higher-MAA variants were the ones that held up in the presence of divalent cations.
Screening five variants in an afternoon of FSEC is cheaper than optimising one polymer for a month. That is what the screening kit is for.