G-Quadruplex Recognition by Tetraalkylammonium Ions: A New Paradigm for Discrimination between Parallel and Antiparallel G-Quadruplexes
Bibliographic record
Abstract
G-quadruplexes are an important class of noncanonical secondary structures of DNA that exist in the cell and are involved in the regulation of principal genomic events. Any regulatory role of a G-quadruplex in the genome is coupled with the attendant interconversions between the G-quadruplex and duplex states. Much effort has been invested in the quest for agents that can recognize individual G-quadruplexes and shift the associated duplex-G-quadruplex equilibria toward the G-quadruplex state. In this communication, we demonstrate that, notwithstanding their simplicity, tetraalkylammonium ions, [H(CH 2 ) n ] 4 N +, recognize and strongly stabilize the parallel c-MYC G-quadruplex, while not binding to the antiparallel human telomeric G-quadruplex or duplex DNA. The affinity of TAA + ions for the c-MYC G-quadruplex correlates with the length of the aliphatic side chains. Our CD spectral data suggest that the binding of tetraalkylammonium ions is external, not resulting in structural changes in the host G-quadruplex. The observed discriminatory power identifies tetraalkylammonium salts as a starting point for developing topology-selective G-quadruplex-binding agents.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".