Electron transfer in DNA duplexes containing 2-methyl-1,4-naphthoquinone
Bibliographic record
Abstract
2-methyl-1,4-naphthoquinone (menadione, MQ) was linked to synthetic oligonucleotides and exposed to near-UV light to generate base radical cations in DNA. This model system of electron transfer induced alkali-labile breaks at GG doublets, similar to anthraquinone and metallointercalators systems. In sharp contrast to other systems, the photolysis of MQ-DNA duplexes gave interstrand cross-links and alkali-labile breaks at bases on the complementary strand opposite the MQ moiety. For sequences with an internal MQ, the formation of cross-links with A and C opposite the MQ moiety was 2- to 3-fold greater than that with G and T. The yield of cross-links was more than 10-fold greater than that of breaks opposite MQ, which in turn was more than 2-fold greater than breaks at GG doublets. The yield of damage at GG doublets greatly increased for a sequence with a terminal MQ. The distribution of base damage was measured by enzymatic digestion and HPLC analysis (dAdo > dThd > dGuo > dCyd). The formation of novel products in MQ-DNA duplexes was attributed to the ability of excited MQ to generate the radical cations of all four DNA bases; thus, this photochemical reaction provides an ideal model system to study the effects of ionizing radiation and one-electron oxidants.
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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 | 0.000 |
| 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".