Besides Fibrillization: Putative Role of the Peptide Fragment 71–82 on the Structural and Assembly Behavior of α-Synuclein
Bibliographic record
Abstract
The fibrillization of α-synuclein (α-syn) is involved in Parkinson's disease, a neurodegenerative disorder that affects four million people in the world. The amino acid sequence 71-82 of this protein (VTGVTAVAQKTV) has appeared to be essential for fibril formation. In the present study, we have investigated the secondary structure and thermal stability of the peptide fragment 71-82, α-syn71-82, as a function of concentration and temperature, as well as its interactions with phospholipid model membranes using various spectroscopic techniques. The data show that α-syn71-82 is mainly disordered in solution with the presence of a few β-sheet structure elements. The peptide reversibly forms intermolecular β-sheets with increasing concentration and decreasing temperature, suggesting that it is subjected to a thermodynamic equilibrium between a monomeric and an oligomeric form. This equilibrium seems to be affected by the presence of zwitterionic membranes. Conversely, the influence of the peptide on zwitterionic lipid bilayers is small and concentration-dependent. By contrast, α-syn71-82 is strongly affected by anionic vesicles. The peptide indeed exhibits a dramatic conformational change, reflecting an extensive and irreversible self-aggregation, the majority of the amino acids being involved in a parallel β-sheet conformation. The aggregates appear to be located near the membrane surface but do not perturb significantly the membrane order. Comparing these results with the literature, it appears that α-syn71-82 shares several general properties and structural similarities with its parent protein. These common points suggest that the sequence 71-82 may overall contribute to the behavior and properties of α-syn.
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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) | 0.001 | 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".