Simultaneous determination of the reduction of NAD <sup>+</sup> and NADP <sup>+</sup> by glutamate dehydrogenase supports preferential utilization of NAD <sup>+</sup> in glutamate oxidation
Bibliographic record
Abstract
The mitochondrial enzyme glutamate dehydrogenase ([GDH] E.C. 1.4.1.3 ) is unusual amongst vertebrate NAD(P) + dependent dehydrogenases in that it can utilize either NAD + or NADP + , and their reduced counterparts, with similar efficiency. Although NADP + typically displays lower maximal velocities, the apparent affinity of GDH for this cofactor is somewhat lower than that for NAD + . The goal of the present study was to determine which cofactor is preferentially reduced when both are present at equal concentrations. First we describe methodology developed for the simultaneous determination of NAD + and NADP + reduction by GDH. We then apply this technique to determine which cofactor, NAD + or NADP + , is preferentially reduced when present in equimolar concentrations, particularly in the presence of known allosteric effectors of GDH, including inhibitory (GTP) as well as activating (leucine and ADP) compounds and combinations thereof. The reduction of NADP + is unaffected by equimolar amounts of NAD + whereas the rate of NAD + reduction is inhibited by the presence of NADP + . Moreover, NADP + shows a modestly higher relative activation by ADP and leucine. However, under all conditions tested, the absolute rate of NAD + reduction was approximately 2–2.5 times that of NADP + , indicating that when both cofactors are present, NAD + is preferentially reduced relative to the rate of NADP + reduction.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".