Tuning of the Prolyl<i>trans</i>/<i>cis</i>-Amide Rotamer Population by Use of<i>C</i>-Glucosylproline Hybrids
Bibliographic record
Abstract
We describe the synthesis of a fused bicyclic C-glucosylproline hybrid (GlcProH) from commercially available 2,3,4,6-tetra-O-benzyl-d-glucopyranose. The GlcProH was incorporated into the model peptides Ac-GlcProH-NHMe and Ac-Gly-GlcProH-NHMe. Postsynthetic modifications can be introduced via derivatization of the carbohydrate scaffold. Conformational analysis of the GlcProH-modified model peptides shows that while the conformation of GlcProH remains fixed, the prolyl N-terminal amide equilibrium (Kt/c) can be varied with different modifications of the carbohydrate scaffold. Simple N-acyl derivatives studied by NMR spectroscopy showed that in CD3OD there was an increase in the cis-amide content as the sugar substituents changed from benzyl (10%) to hydroxyl (22%) to acetate (36%). Similar effects were observed in DMSO-d6. The exact nature of the influence is unclear, but it most likely arises through intramolecular interactions between sugar groups and the peptidic amide backbone. Overall, our GlcProH demonstrates variation in Kt/c through tuning of the carbohydrate scaffold: a new concept in proline peptidomimetics.
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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".