A Potentially Prebiotic Synthesis of a 3′-Amino-3′-deoxyribonucleoside
Bibliographic record
Abstract
A central challenge in origins of life research is understanding how primitive genetic polymers could have replicated nonenzymatically prior to the evolution of macromolecular catalysts. Such a process would have required the formation of inter-nucleotide linkages, high fidelity in nucleobase pairing, and the ability to produce oligomers of sufficient length within short timescales. While modern ribozymes capable of catalyzing phosphodiester bond formation provide a model for RNA-based catalysis, they require a typical minimum length of ~50 nucleotides, a size unlikely to arise spontaneously without enzymatic intervention. Studies have demonstrated that the substitution of the canonical 3′-OH group with the much more nucleophilic 3′-NH2 group significantly enhances nonenzymatic template-directed oligomerization, and may have enabled early genetic polymers to bypass the need for enzymatic catalysis. Here, we report the synthesis of a 3′-amino-3′-deoxyribocytidine from prebiotic feedstocks. Our results support the hypothesis that 3′-amino-modified ribonucleotides could have served as substrates for the nonenzymatic synthesis of phosphoramidate nucleic acids on the early Earth prior to the emergence of RNA and ribozymes.
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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) | 0.001 | 0.001 |
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".