Novel NADPH-dependent L-aspartate dehydrogenases from the mesophilic nitrogen-fixing bacteria Rhodopseudomonas palustris and Bradyrhizobium japonicum
Bibliographic record
Abstract
The genes encoding putative L-aspartate dehydrogenases (EC 1.4.1.21, ADH) from the mesophilic nitrogen-fixing bacteria Rhodopseudomonas palustris and Bradyrhizobium japonicum were cloned and expressed in Escherichia coli. The respective enzymes in the form of hybrid proteins with N-terminal hexahistidine tags were purified to apparent homogeneity. Both enzymes catalyzed in vitro the reductive amination of oxaloacetate to L-aspartate by an order faster than the reverse reaction at a respective pH optimum of 8.0-9.0 and 9.8; also, the enzymes only catalyzed amination under physiological conditions (pH 7.0-8.0). Their specificity to NADPH was higher by 1-2 orders of magnitude than that to NADH. The apparent KM values of ADHs from R. palustris for oxaloacetate, ammonium, and NADPH at pH 9.0 were 9.2, 11.3, and 0.21 mM, respectively, and the corresponding KM values of ADH from B. japonicum were 21, 4.3, and 0.032 mM, respectively. The amination activity of novel ADHs may be important for the fixation of inorganic nitrogen in vivo and used for the construction of a bacterial strain-producer of L-aspartate by metabolic engineering methods.
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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) | 0.001 | 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".