Protomers of DNA-binding dye fluoresce different colours: intrinsic photophysics of Hoechst 33258
Bibliographic record
Abstract
to the red of the first form. Quantum chemical calculations reveal that this second population is likely a newly-identified protomer, which is considerably more stable in the gas phase than conformations with the solution protonation site. Two routes that increase the fluorescence of H33258 in solution - formation of the diprotomer and complexation with dsDNA - do not produce an increase in fluorescence in the gas phase. However, two other outcomes parallel behaviour. First, the similarity of action spectra of the gaseous dsDNA-H33258 complex and the unbound diprotomer suggest that the dye may be diprotomeric when in complex with gaseous dsDNA. Second, the photodissociation power dependence measurements indicate the presence of at least two distinct populations of both H33258 in complex with dsDNA and in its unbound diprotomeric form. Overall, the results reported here reveal unexplored aspects of the potential energy landscape of H33258, including a new, stable, highly-fluorescent form that may be useful to consider in sensing applications. Moreover, the results reinforce how structure, deactivation pathways and other photophysical properties are intertwined for this DNA-binding dye, which may offer strategies for improved control of DNA-targeting drugs and sensors.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".