Electrospray Ionization Tandem Mass Spectrometry Analysis of the Reactivity of Structurally Related Bromo-methyl-benzoquinones toward Oligonucleotides
Bibliographic record
Abstract
We report the use of electrospray ionization tandem mass spectrometry (ESI-MS/MS) as a tool for rapid screening of structurally related chemicals toward oligonucleotides using the binding of five bromobenzoquinones with single-stranded (ss) and double-stranded (ds) oligonucleotides (ODNs) as a model. We found that these compounds interact differentially with oligonucleotides depending on the extent of their bromination and methylation. Three dibromobenzoquinones, 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ), 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), and 2,5-dimethyl-3,6-dibromo-1,4-benzoquinone (DMDBBQ), bound to ssODN to form 1:1 adducts, and the binding constant of DMDBBQ bound to ssODN was 100-fold lower than those of 2,6-DBBQ and 2,5-DBBQ to ssODN, indicating that methyl groups hindered interactions of the bromoquinones with ODNs. Collision-induced dissociation (CID) of the 1:1 and 1:2 adducts of ODN with 2,6-DBBQ and 2,5-DBBQ demonstrated neutral loss of DBBQ and charge separations. Incubation of two tetrabromobenzoquinones (TBBQ), 2,3,5,6-tetrabromo-1,4-benzoquinone and 3,4,5,6-tetrabromo-1,2-benzoquinone, with the same ODNs did not form any adducts of TBBQ with ssODN or dsODN; however, bromide-ODNs were detected. Fragmentation of the bromide-ODN adducts showed loss of the HBr molecule, supporting the presence of bromide on ODNs. High-resolution MS and MS/MS analysis of the mixtures of dinucleotides (AA, GG, CC, and TT) and TBBQ confirmed the presence of bromide on the dinucleotides, supporting the transfer of bromide to ODNs through interaction with TBBQ. This study presents evidence of differential interactions of structurally related bromo and methyl-benzoquinones with oligonucleotides and demonstrates a potential application of ESI-MS/MS analysis of chemical interactions with ODN for rapid screening of the reactivity of other structurally related environmental contaminants toward DNA.
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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".