Probing electrostatic interactions in cytochrome <i>c</i> using site-directed chemical modification
Bibliographic record
Abstract
This communication reports the generation of an electrostatic probe using chemical modification of methionine side chains. The alkylation of methionine by iodoacetamide was achieved in a set of Saccharomyces cerevisiae iso-1-cytochrome c mutants, introducing the nontitratable, nondelocalized positive charge of a carboxyamidomethylmethionine sulfonium (CAMMS) ion at five surface and one buried site in the protein. Changes in redox potential and its variation with temperature were used to calculate microscopic effective dielectric constants operating between the probe and the heme iron. Dielectric constants (epsilon) derived from deltadeltaG values were not useful due to entropic effects, but epsilon(deltadeltaH) gave results that supported the theory. The effect on biological activity of surface derivatization was interpreted in terms of protein-protein interactions. The introduction of an electrostatic probe in cytochrome c often resulted in marked effects on activity with one of two physiological partners: cytochrome c reductase, especially if introduced at position 65, and cytochrome c oxidase, if at position 28.
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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".