X‐ray structure analysis reveals <i>β</i>‐turn mimicry by <i>N</i>‐amino‐imidazolidin‐2‐ones<sup>†</sup>
Bibliographic record
Abstract
The conformation of the N-amino-imidazolidin-2-one (Aid) peptidomimetic was investigated using NMR spectroscopy and X-ray crystallography. In solution, the tetrapeptide model p-bromobenzoyl-Aid-l-Phe-N'-iso-propylamide (1) exhibited shielded and solvent exposed amide protons indicative of a turn conformation. In the crystal lattice of 1, four turn conformers were present in the unit cell differing primarily by the ring puckering of the Aid residue. Two pairs of β-turn conformers were observed each possessing an intramolecular ten-member hydrogen bond between the benzamide carbonyl and iso-propylamine NH moieties. The pairs had types II and II' β-turn geometry that differed slightly about the ϕ and ψ torsion angles. Moreover, the X-ray analysis of 1 has been compared with that of the related unsaturated N-amino-imidazolin-2-one (Nai) analogs indicating the influences of ring flattening and substituents on conformation. Insertion of the preorganized Aid structure into biologically active peptides has thus been shown to offer a potentially valuable means for exploring the importance of turn geometry for activity, particularly in drug discovery.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| 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 teacher head, 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".