Spermidine/spermine n(1)-acetyltransferase catalyzes amantadine acetylation.
Bibliographic record
Abstract
Amantadine acetylation was demonstrated to occur both in vivo and in vitro using transgenic male mice overexpressing spermidine/spermine N(1)-acetyltransferase (SSAT). We previously reported that neither NAT1 nor NAT2 was responsible for catalyzing acetylation of the primary amine group of amantadine. We hypothesized that the inducible polyamine-catabolizing enzyme, SSAT, was an alternate pathway for acetylating amantadine. Transgenic mice injected s.c. with 3 mg/kg amantadine excreted 4.5 +/- 1% (mean +/- S.E.) of the administered dose as acetylamantadine in 24-h urine samples while, by contrast, nontransgenic control mice failed to excrete any detectable acetylamantadine in their urine. In vitro studies with the cytosolic liver fraction from transgenic mice as the source of SSAT demonstrated spermidine acetylation catalytic activity with an apparent K(m) = 267 +/- 46 microM and V(max) = 0.009 +/- 0.002 nmol/min/mg of protein. Amantadine competitively inhibited spermidine acetylation with an apparent K(i) = 738 +/- 157 microM. Incubation of amantadine, SSAT, and an acetyl CoA-regenerating system produced modest amounts of acetylamantadine. The NAT2 substrate, sulfamethazine, inhibited spermidine acetylation with a calculated K(i) = 3.5 mM, suggesting that SSAT may be an alternate pathway for acetylation of NAT2 substrates. The NAT1 substrate, p-aminobenzoic acid, had no inhibitory effect. These results provide evidence that amantadine can be acetylated by SSAT and may be a specific drug substrate for this enzyme. Further investigation of the role of SSAT as a potential drug-metabolizing pathway is warranted.
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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".