Characterization of recombinant prolidase from <i>Lactococcus lactis</i>– changes in substrate specificity by metal cations, and allosteric behavior of the peptidase
Bibliographic record
Abstract
The Lactococcus lactis NRRL B-1821 prolidase gene was cloned and overexpressed in Escherichia coli. Under suboptimum growth conditions, recombinant soluble and active prolidase was produced; in contrast, inclusion bodies were formed under conditions preferred for cell growth. Recombinant prolidase retained more than half its full activity between 30 and 60 degrees C, and was completely inactivated after 30 min at 70 degrees C. CD analysis confirmed that prolidase was inactivated at 67 degrees C. The enzyme was active under weak alkali to weak acidic conditions, and showed maximum activity at pH 7.0. Although these characteristics are similar to those for other reported prolidases, this prolidase was distinctive for two kinetic characteristics. Firstly, different substrate specificity was observed for its two preferred metal cations, zinc and manganese: Leu-Pro was preferred with zinc, whereas Arg-Pro was preferred with manganese. Secondly, the enzyme showed an allosteric response to changes in substrate concentrations, with Hill constants of 1.53 for Leu-Pro and 1.57 for Arg-Pro. Molecular modeling of this prolidase suggests that these unique characteristics may be attributed to a loop structure near the active site.
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 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 | 0.000 |
| 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 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".