Conformational Flexibility of C8-Phenoxylguanine Adducts in Deoxydinucleoside Monophosphates
Bibliographic record
Abstract
M06-2X/6-31G(d,p) is used to calculate the structure of all natural deoxydinucleoside monophosphates with G in the 5' or 3' position, the anti or syn conformation, and each natural (A, C, G, T) base in the corresponding flanking position. When the ortho or para C8-phenoxyl-2'-deoxyguanosine (C8-phenoxyl-dG) adduct replaces G in each model, there is little change in the relative base-base orientation or backbone conformation. However, the orientation of the C8-phenoxyl group can be characterized according to the position (5' versus 3'), conformation (anti versus syn), and isomer (ortho versus para) of damage. Although the degree of coplanarity between the phenoxyl ring and G base in the ortho adduct is highly affected by the sequence since the hydroxyl group can interact with neighboring bases, the para adduct generally does not exhibit discrete interactions with flanking bases. For both adducts, steric clashes between the phenoxyl group and the backbone or flanking base destabilize the anti conformation preferred by the natural nucleotide and thereby result in a clear preference for the syn conformation regardless of the sequence or position. This contrasts the conclusions drawn from smaller (nucleoside, nucleotide) models previously used in the literature, which stresses the importance of using models that address the steric constraints present due to the surrounding environment. Since replication errors for other C8-dG bulky adducts have been linked to a preference for the syn conformation, our findings provide insight into the possible mutagenicity of phenolic adducts.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".