Roles of Salt and Conformation in the Biological and Physicochemical Behavior of Protegrin-1 and Designed Analogues: Correlation of Antimicrobial, Hemolytic, and Lipid Bilayer-Perturbing Activities
Bibliographic record
Abstract
Protegrins are short (16-18 residues) cationic peptides from porcine leukocytes that display potent, broad-spectrum antimicrobial activity. Protegrin-1 (PG-1), one of five natural homologues, adopts a rigid beta-hairpin structure that is stabilized by two disulfide bonds. We have previously employed the principles of beta-hairpin design to develop PG-1 variants that lack disulfide bonds but nevertheless display potent antimicrobial activity [Lai, J. R., Huck, B. R., Weisblum, B., and Gellman, S. H. (2002) Biochemistry 41, 12835-12842.]. The activity of these disulfide-free variants, however, is attenuated in the presence of salt, and the activity of PG-1 itself is not. Salt-induced inactivation of host-defense peptides, such as human defensins, is thought to be important in some pathological situations (e.g., cystic fibrosis), and the variation in salt-sensitivity among our PG-1 analogues offers a model system with which to explore the origins of these salt effects. We find that the variations in antimicrobial activity among our peptides are correlated with the folding propensities of these molecules and with the extent to which the peptides induce leakage of contents from synthetic liposomes. Comparable correlations were observed between folding and hemolytic activity. The extent to which added salt reduces antimicrobial activity parallels salt effects on vesicle perturbation, which suggests that the biological effects of high salt concentrations arise from modulation of peptide-membrane interactions.
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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 | 0.000 | 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) | 0.000 | 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".