Model Calculations Relevant to Disulfide Bond Cleavage via Electron Capture Influenced by Positively Charged Groups
Bibliographic record
Abstract
Ab initio electronic structure calculations are used to explore the effect of nonneighboring positively charged groups on the ability of low-energy (<1 eV) electrons to directly attach to S−S σ bonds in disulfides to effect bond cleavage. It is shown that, although direct vertical attachment to the σ* orbital of an S−S σ bond is endothermic, the stabilizing Coulomb potential produced in the region of the S−S bond by one or more distant positive groups can render the S−S σ* anion state electronically stable. This stabilization, in turn, can make near vertical electron attachment exothermic. The focus of these model studies is to elucidate a proposed mechanism for bond rupture that may, in addition to other mechanisms, be operative in electron capture dissociation (ECD) experiments. The importance of these findings lies in the fact that a more complete understanding of how ECD takes place will allow workers to better interpret ECD fragmentation patterns observed in mass spectrometric studies of proteins and polypeptides.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".