NMR Structure of an Ethylene Interstrand Cross‐Linked DNA which Mimics the Lesion Formed by 1,3‐Bis(2‐chloroethyl)‐1‐nitrosourea
Bibliographic record
Abstract
The bisalkylating agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), used in cancer chemotherapy to hinder cellular proliferation, forms lethal interstrand cross-links (ICLs) in DNA. BCNU generates an ethylene linkage connecting the two DNA strands at the N1 atom of 2'-deoxyguanosine and N3 atom of 2'-deoxycytidine, which is a synthetically challenging probe to prepare. To this end, an ICL duplex linking the N1 atom of 2'-deoxyinosine to the N3 atom of thymidine via an ethylene linker was devised as a mimic. We have solved the structure of this ICL duplex by a combination of molecular dynamics and high-field NMR experiments. The ethylene linker is well-accommodated in the duplex with minimal global and local perturbations relative to the unmodified duplex. These results may account for the substantial stabilization of the ICL duplex observed by UV thermal denaturation experiments and provides structural insights of a probe that may be useful for DNA repair studies.
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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 | 0.000 | 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| 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".