Plant Protein Proteinase Inhibitors: Structure and Mechanism of Inhibition
Bibliographic record
Abstract
This review outlines known examples of the three-dimensional structures of protein proteinase inhibitors from plants. Three families of enzymes, serine proteinases, carboxypeptidases and cysteine proteinases, are targeted by at least a dozen inhibitor families, with the majority of them adopting the standard mechanism of inhibition towards the serine proteinases. All of the inhibitors discussed maintain compact and stable inhibitory domains that bind to the active site of their target proteinases and prevent access to the substrate molecules. One interesting highlight is the knottin group. Three separate inhibitor families utilize the overall knottin fold in a different way. This fold can accommodate extensive sequence variation and for each of the squash, Mirabilis and Potato carboxypeptidase families, the proteinase-binding residues are found at a different location. Plants have also evolved additional strategies to regulate proteinase activity, such as linking inhibitory domains and targeting multiple enzymes at once. The structural aspects of these strategies are discussed in the review. Keywords: Plant protein proteinase inhibitor, three-dimensional structure, reactive-site loop, standard mechanism, Inhibition mechanism, plant protease inhibitors, serine proteinases, carboxypeptidases, inhibitor families, cysteine proteinases, inhibitory domains, Mirabilis, knottin group, suppositions, tissue, NMR methods, X-ray
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.002 |
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".