Mechanistic and Kinetic Insights into Nucleobase Oxidation: Detection of Radical Intermediates in Thymine Oxidation Using SH2′ Radical Trapping
Bibliographic record
Abstract
Short-lived radical intermediates, such as reactive oxygen species (ROS), play a crucial role in oxidative stress, aging, and carcinogenesis. However, understanding of these processes is impeded by limitations of existing radical characterisation techniques. Previous investigations demonstrated that the recently-developed SH2′ radical trapping technique could be used to probe biochemical oxidation mechanisms. In this study, SH2′ radical trapping and mass spectrometry (MS) techniques were used to investigate ●OH-initiated degradation of thymine, relevant to oxidative damage of DNA. Numerous substrate-derived radical intermediates were trapped and characterised, aiding elucidation of, and offering validation to, proposed mechanisms. Isotope exchange and chromatographic separations helped to distinguish between isomeric structures. Observation of thymine dimer radicals and products suggests that this methodology can be useful for studying radical cross-linking of nucleobases. Overall, SH¬2′ radical trapping was demonstrated to be a powerful technique for investigating oxidation pathways in biological systems.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".