The Two Classic Pb<sup>2+</sup>‐Selective DNAzymes Are Related: Rational Evolution for Understanding Metal Selectivity
Bibliographic record
Abstract
Abstract In 1994, the first DNAzyme named GR5 was reported, which specifically requires Pb 2+ for its RNA cleavage activity. Three years later, the 8‐17 DNAzyme was isolated. The 8‐17 DNAzyme and the related 17 E DNAzyme are also most active with Pb 2+ , although other divalent metals can work as well. GR5 and 17 E have the same substrate sequence, and their catalytic loops in the enzyme strands also have a few similar and conserved nucleotides. Considering these, we hypothesized that 17 E might be a special form of GR5. To test this hypothesis, we performed systematic rational evolution experiments to gradually mutate GR5 toward 17 E . By using the activity ratio in the presence of Pb 2+ and Mg 2+ for defining these two DNAzymes, the critical nucleotide was identified to be T 12 in 17 E for metal specificity. In addition, G 9 in GR5 is a position not found in most 17 E or 8‐17 DNAzymes, and G 9 needs to be added to rescue GR5 activity if T 12 becomes a cytosine. This study highlights the links between these two classic and widely used DNAzymes, and offers new insight into the sequence–activity relationship related to metal selectivity.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".