Pb<sup>2+</sup> as a Substrate and a Cofactor of a Porphyrin Metalation DNAzyme
Bibliographic record
Abstract
Abstract We herein report a DNAzyme named T30695 (sequence: (G 3 T) 4 ) that can catalyze Zn 2+ insertion into three different porphyrins in the presence of Pb 2+ as a cofactor. Meanwhile, T30695 with Pb 2+ alone was found to cause a shift in both the fluorescence and UV‐vis spectra of protoporphyrin IX (PPIX), thus suggesting that metalation of Pb 2+ was also achieved at room temperature. From kinetic measurements, the reaction required two Pb 2+ ions; this is consistent with one being a cofactor and the other being a substrate. No previous reports inserted Pb 2+ into porphyrins by using DNAzymes or protein‐based enzymes. This reaction was most significantly inhibited in the presence of K + followed by Na + and Li + , suggesting the importance of the Pb 2+ ‐stabilized G‐quadruplex. When Pb 2+ is inserted into PPIX, its emission blue shifts from 635 to 590 nm, thus allowing simple ratiometric fluorescent sensing with a detection limit of 1.2 nM Pb 2+ .
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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 | 0.001 | 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".