Evidence by infrared spectroscopy of the presence of two types of β-sheets in major ampullate spider silk and silkworm silk
Bibliographic record
Abstract
The major ampullate (MA) silk of spider is known to be composed of oriented β-sheet nanocrystals dispersed within an amorphous matrix. The presence of an interphase has also been proposed, but it has not been reported for the fibroin of the silkworm Bombyx mori (B. mori). To obtain quantitative information regarding this third phase, the deuteration of B. mori silk and Nephila clavipes MA silk has been probed by attenuated total reflection infrared spectroscopy. The spectral decomposition of the amide II region has allowed determination of the level of orientation and content of the different secondary structures. The data reveal that, in addition to the amorphous domains, part of the β-sheets is deuterated upon immersion in D2O for both silks. The D2O-inaccessible β-sheets are associated with crystallites, while the interphase is composed of D2O-accessible ones. It is found that the former β-sheets are slightly more oriented along the fiber axis than the latter ones, which suggests that the interphase β-sheets are located at both ends of the crystals. The total β-sheet content is similar for B. mori silk (50 ± 4%) and MA silk (46 ± 4%). However, 27 ± 3% of the β-sheets of MA silk are D2O-accessible compared to 8 ± 3% for B. mori silk. These data suggest that around 5 amino acids for B. mori silk and 9 amino acids for MA silk would be involved in the interphase β-sheets. The higher amount of interphase β-sheets for MA silk is believed to contribute to its higher toughness.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".