The role of proline in the elastic mechanism of hydrated spider silks
Bibliographic record
Abstract
This study used thermoelastic measurements to investigate the role of proline in the elastic mechanism of hydrated, spider major ampullate (MA) and flagelliform (FL) silks. Experiments on hydrated MA silk from Araneus diadematus (proline content 16%) reveal that conformational entropy elasticity accounts for about 90% of the elastic force at small extensions, but entropy elasticity drops to about half by 50% extension. The decrease in the entropic component with extension is due to the presence of relatively short and conformationally restricted network chains in Araneus MA silk. Experiments on hydrated Araneus FL silk (proline content 16%) indicate that entropy elasticity dominates the elastic mechanism up to extensions of 100% and beyond, which likely reflects the fact that the glycine-rich network chains in FL silk are longer and less conformationally restricted than those in the MA silk. Thus, the rubber-like, entropic elasticity of these two proline-rich silks is consistent with networks of amorphous chains that become mobile when hydrated. By contrast, the elastic mechanism of hydrated Nephila clavipes MA silk (proline content 3.5%) shows a small contribution from entropic elasticity for extensions of 5% or less, and by 10% extension the elastic force is due entirely to bond-energy elasticity, probably associated with the deformation of stable secondary structures. These results indicate that there are major differences in the structural organization of the glycine-rich network chains and the mechanism of elasticity in proline-rich and proline-deficient fibroins.
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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".