Extended Apolar β-Peptide Foldamers: The Role of Axis Chirality on β-Peptide Sheet Stability
Bibliographic record
Abstract
This study is on structure and stability of sheetlike conformers of beta-peptides; never seen new foldamers are reported here for the first time. Single- and double-stranded structures are analyzed, and the seeds of large beta-layers and biocompatible nanomaterials are described here. Both the monomeric, HCO-[NH-CH(2)-CH(2)CO](n)-NH(2), and dimeric forms, [HCO-(beta-Ala)(n)-NH(2)](2) n = 3 and 4, of oligo-beta-alanine supramolecular complexes are evaluated by using an adequate level of theory M052X/6-31G(d) for peptides of this size. Polymers composed of backbone foldamers with the central mu torsion angle set to an anti orientation were all probed. Sheet structures built up of strands with carbonyl groups monotonically facing the same spatial direction, polar strands, were previously assigned and synthesized ( Seebach , D. Chem. Biodiversity 2004 , 1 , 1111 - 1239 ). Now we are presenting a novel beta-peptide sheet structure of alternating carbonyl group orientations, called as apolar strands. These novel secondary structural elements of beta-peptides are structural analogs of beta-pleated sheets of proteins. Interestingly enough, the latter type of apolar strands are foreseen as very stable supramolecular complexes and are more firm by approximately 10 kcal.mol(-1) than the aforementioned polar strands. Furthermore, apolar strands lack the inherent twisting of beta-layers, present in polar strands resulting in the tubular shape. Once the effect of substitution of Hbeta1 and/or Hbeta2 atoms are revealed on foldamer stability, short peptide sequence could be designed and synthesized. These new, conformationally optimized beta-sheetlike nanostructures of increased stability with little or no twisting could be used as enzymatically resistant ( Frackenpohl , J. , Arvidsson , P. I. , Schreiber , J. V. , and Seebach , D. ChemBioChem 2001 , 2 , 445 - 455 ) biomaterials. These newly designed models systems could enlarge the arsenal of durable polyesters of similar chemical constitution (e.g., -[O-CH(CH(3))-CH(2)CO](n)- and -[O-CH(COOH)-CH(2)CO](n)-) already used as artificial heart valves, for example.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".