New Short Peptide Substrates of Endothelin-Converting Enzyme and Characterization of the Enzyme
Bibliographic record
Abstract
Endothelin (ET) is a 21 amino acid peptide produced following the cleavage of its precursor, big ET, by a metalloprotease, the endothelin-converting enzyme (ECE). In the study reported here we determined the minimal peptide sequence of big ET necessary for enzyme recognition and cleavage at the P1-P1' site. Furthermore, we have explored the role of the amino acids found at the boundaries of the cleavage site. To reach these goals. we synthesized a series of fragments, all containing the P1-P1' cleavage site, Trp21-Val22. Following the incubation of peptide fragments with a partly purified bovine ECE preparation and after analyzing the cleavage pattern by high-performance liquid chromatography (HPLC), we were able to identify big ET(18-23) amide as the minimal peptide core recognized and cleaved by the enzyme. This hydrolysis was inhibited by phosphoramidon but not by thiorphan, a characteristic of the ECE metalloprotease. However, none of the shorter peptides was able to inhibit the cleavage of big ET-1 by ECE, suggesting that they are not recognized by the enzyme. Particularly, it appears that aspartic acid 18 is a key residue for the recognition phenomenon. The delineation of the minimal structure will be a useful tool to further characterize ECE.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".