Exploring the Potent Inhibition of CTP Synthase by Gemcitabine‐5′‐Triphosphate
Bibliographic record
Abstract
Abstract CTP synthase (CTPS) catalyzes the conversion of UTP to CTP and is a target for the development of antiviral, anticancer, antiprotozoal, and immunosuppressive agents. Exposure of cell lines to the antineoplastic cytidine analogue gemcitabine causes depletion of intracellular CTP levels, but the direct inhibition of CTPS by its metabolite gemcitabine‐5′‐triphosphate (dF‐dCTP) has not been demonstrated. We show that dF‐dCTP is a potent competitive inhibitor of Escherichia coli CTPS with respect to UTP [ K i =(3.0±0.1) μ m ], and that its binding affinity exceeds that of CTP ≈75‐fold. Site‐directed mutagenesis studies indicated that Glu149 is an important binding determinant for both CTP and dF‐dCTP. Comparison of the binding affinities of the 5′‐triphosphates of 2′‐fluoro‐2′‐deoxycytidine and 2′‐fluoro‐2′‐deoxyarabinocytidine revealed that the 2′‐F‐ arabino group contributes markedly to the strong binding of dF‐dCTP. Geminal 2′‐F substitution on UTP (dF‐dUTP) did not result in an increase in binding affinity with CTPS. Remarkably, CTPS catalyzed the conversion of dF‐dUTP into dF‐dCTP, thus suggesting that dF‐dCTP might be regenerated in vivo from its catabolite dF‐dUTP.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".