Near-UV Photolysis of 2-Methyl-1,4-naphthoquinone−DNA Duplexes: Characterization of Reversible and Stable Interstrand Cross-Links between Quinone and Adenine Moieties
Bibliographic record
Abstract
Near-UV photolysis of 2-methyl-1,4-naphthoquinone (MQ, menadione) tethered DNA induces initial charge transfer followed by either transport of the damage to G or the formation of interstrand cross-links between MQ and DNA bases. In this work, the products responsible for interstrand cross-links have been characterized by mass spectrometry, NMR, and comparison with model compounds. Three major products were formed in the photolysis of MQ-DNA duplexes. Two of the products (isomers) have a cross-link between C2 of a 2,3-saturated MQ moiety and N6 of a dAdo moiety. These products readily convert back to MQ and dAdo upon heating in neutral solution, and thus, they lead to reversible cross-links in MQ-DNA duplexes. The third product has a cross-link between C3 of a 2,3-unsaturated MQ moiety and N6 of an dAdo moiety. This product was stable in neutral solution. The formation of MQ to A cross-links in DNA may be explained by the coupling of MQ radicals that arise from the protonation of MQ radical anions, together with adenin-N6-yl radicals that arise from the deprotonation of A radical cations.
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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".