Chirality recognition of the protonated serine dimer and octamer by infrared multiphoton dissociation spectroscopy
Bibliographic record
Abstract
Infrared multiphoton dissociation (IRMPD) spectroscopy has been used to record IR signatures of chirality recognition in the protonated serine dimer and octamer in the 3200-3800 cm(-1) region. This is the first IRMPD study to investigate the heterochiral biomolecular system by utilizing the isotope-labelled species. Noticeable differences in the homo- versus heterochiral IRMPD spectra have been obtained experimentally for both the dimer and octamer. Different dissociation patterns have been noted not only between the homo- and heterochiral octamers, but also between the two -OH stretching vibrational bands of the same chirality species. Systematic theoretical searches have been carried out to identify the most stable conformers of both the homo- and heterochiral protonated serine dimer and octamer. The final geometry optimization and harmonic vibrational calculations have been performed at the MP2/6-311++G(d,p) level for the homo- and heterochiral protonated serine dimer and at the B3LYP/6-31G(d) level for the homo- and heterochiral protonated serine octamer. For the homo- and heterochiral dimer, good agreement between the experimental and theoretical spectra has been achieved and the major conformers have been identified. For the homo- and heterochiral octamer, the main IR features observed have been satisfactorily reproduced theoretically and the dominant conformers identified. More than one main conformer has been identified for the homochiral octamer. This conclusion has been further supported by the analysis of the wavelength specific dissociation products.
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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".