Design of zwitterionic fluorescent polymers for membrane protein solubilization into native nanodiscs
Bibliographic record
Abstract
Copolymers formed by non-alternating distributions of styrene and maleic acid monomers directly solubilize intact membranes into ∼10 nm discs. However, these copolymers are inherently polydisperse in terms of polymer structure, difficult to detect, prone to precipitation with divalent cations, and have limited working pH ranges due to their charges. The exposed polar sidechain of nanodisc-forming amphipathic copolymers provides a handle for integrating critical chemical features for facile solubilization, purification, detection, and resolution of diverse membrane protein complexes, including 7-transmembrane G-Protein-Coupled Receptor (GPCR) and beta-barrel proteins directly from cellular material. Here, we report that when derivatized with amine oxide (AO) moieties, alternating and intrinsically fluorescent derivatives of poly(styrene- alt -maleic anhydride) (SMAnh) spontaneously convert biological membranes into nanodiscs with diameters of 15–30 nm that can be resolved by dynamic light scattering and electron microscopy. Compared to non-alternating poly(styrene- co -maleic acid) (SMA), their fluorescence signals allow monitoring under diverse solution conditions, whether free or lipid bilayer-bound. These copolymers are useful in a broad pH range, are tolerant of high levels of divalent cations (>200 mM CaCl 2 ) and are designed to reduce undesirable nonspecific interactions. The resulting nanodiscs can accommodate the PagP palmitoyltransferase expressed in Escherichia coli outer membranes and the human adenosine A 2A receptor expressed into Pichia pastoris membranes, resulting in readily purified proteins that are less likely to be perturbed by polymer charge or hydrophobicity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".