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 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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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".