Structure-Based Design of an Indolicidin Peptide Analogue with Increased Protease Stability<sup>,</sup>
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Bibliographic record
Abstract
Indolicidin is an antimicrobial cationic peptide with broad-spectrum activity isolated from bovine neutrophils. An indolicidin analogue CP-11, ILKKWPWWPWRRK-NH(2), with improved activity against Gram-negative bacteria had increased positive charge and amphipathicity while maintaining the short length of the parent molecule. The structure of CP-11 in the presence of dodecylphosphocholine (DPC) micelles was determined using nuclear magnetic resonance spectroscopy. CP-11 was found to be an amphipathic molecule with a U-shaped backbone bringing the N- and C-termini in close proximity. On the basis of this close proximity, a cyclic disulfide-bonded peptide cycloCP-11, ICLKKWPWWPWRRCK-NH(2), was designed to stabilize the lipid-bound structure and to increase protease resistance. The three-dimensional structure of cycloCP-11 was determined under the same conditions as for the linear peptide and was found to be similar to CP-11. Both CP-11 and cycloCP-11 associated with phospholipid membranes in a similar manner as indicated by circular dichroism and fluorescence spectra. The minimal inhibitory concentrations of CP-11 and cycloCP-11 for a range of bacteria differed by no more than 2-fold, and they were nonhemolytic at concentrations up to 256 microg/mL. Cyclization was found to greatly increase protease stability. The half-life of cycloCP-11 in the presence of trypsin was increased by 4.5-fold from 4 to 18 min. More importantly, the antibacterial activity of cycloCP-11, but not that of CP-11, in the presence of trypsin was completely retained up to 90 min since the major degradation product was equally active. A structural comparison of CP-11 and cycloCP-11 revealed that the higher trypsin resistance of cycloCP-11 may be due to the more compact packing of lysine and tryptophan side chains. These findings suggest that cyclization may serve as an important strategy in the rational design of antimicrobial peptides.
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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 | 0.001 |
| 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 it