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Record W2115773821 · doi:10.1021/jp0262721

B−Z Conformational Transition of DNA Monitored by Vibrational Circular Dichroism. Ab Initio Interpretation of the Experiment

2002· article· en· W2115773821 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.

Bibliographic record

VenueThe Journal of Physical Chemistry B · 2002
Typearticle
Languageen
FieldChemistry
TopicMolecular spectroscopy and chirality
Canadian institutionsUniversity of Calgary
Fundersnot available
KeywordsVibrational circular dichroismAb initioChemistryMoleculeAb initio quantum chemistry methodsCircular dichroismSpectral lineMolecular physicsCrystallographyComputational chemistryAtomic physicsPhysics

Abstract

fetched live from OpenAlex

The B−Z conformational transition was induced by Mn 2+ ions in a synthetic oligonucleotide (dG-dC) 20 and monitored by the vibrational circular dichroism (VCD). For the first time, the spectra were analyzed on the basis of quantum-mechanical computations. Force field and intensity tensors computed ab initio for smaller DNA fragments were transferred to a d(GCGCGCGC) 2 octamer model including explicit water molecules. The method allowed us to assign and explain most of the frequency and intensity features observed in the absorption and VCD spectra of the B- and Z-forms. Particularly, the computations reproduced the VCD sign flip caused by the transition due to the C O stretching and allowed us to assign most spectral bands in the nitrogen bases vibrational region. Also, known isotopic effects (deuteration and a 18 O substitution) were reproduced correctly. For the sugar−phosphate modes, the assignment of the VCD bands was hindered by a weak experimental signal. The approach based on quantum-mechanical computations was found superior to previous models based on coupled oscillator theory. Water molecules hydrogen-bonded to the DNA skeleton had to be included for reliable interpretation of the VCD and IR spectral patterns, namely, for the sugar−phosphate vibrations.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

Full frame distilled prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.008
Threshold uncertainty score0.430

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

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.

Opus teacher head0.007
GPT teacher head0.230
Teacher spread0.223 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it