Effect of Variations in the Structure of a Polyleucine-Based α-Helical Transmembrane Peptide on Its Interaction with Phosphatidylglycerol Bilayers
Bibliographic record
Abstract
High-sensitivity differential scanning calorimetry and Fourier transform infrared spectroscopy were used to study the interaction of a cationic alpha-helical transmembrane peptide, acetyl-Lys(2)-Leu(24)-Lys(2)-amide (L(24)), and members of the homologous series of anionic n-saturated diacyl phosphatidylglycerols (PGs). Analogues of L(24), in which the lysine residues were replaced by 2,3-diaminopropionic acid (L(24)DAP), or in which a leucine residue at each end of the polyleucine sequence was replaced by a tryptophan (WL(22)W), were also studied to investigate the roles of lysine side-chain snorkeling and aromatic side-chain interactions with the interfacial region of phospholipid bilayers. The gel/liquid-crystalline phase transition temperature of the host PG bilayers is altered by these peptides in a hydrophobic mismatch-dependent manner, as previously found with zwitterionic phosphatidylcholine (PC) bilayers. However, all three peptides reduce the phase transition temperature and enthalpy to a greater extent in anionic PG bilayers than in zwitterionic PC bilayers, with WL(22)W having the largest effect. All three peptides form very stable alpha-helices in PG bilayers, but small conformational changes are induced in response to a mismatch between peptide hydrophobic length and gel-state lipid bilayer hydrophobic thickness. Moreover, electrostatic and hydrogen-bonding interactions occur between the terminal lysine residues of L(24) and L(24)DAP and the polar headgroups of PG bilayers. However, such interactions were not observed in PG/WL(22)W bilayers, suggesting that the cation-pi interactions between the tryptophan and lysine residues predominate. These results indicate that the lipid-peptide interactions are affected not only by the hydrophobic mismatch between these peptides and the host lipid bilayer, but also by the tryptophan-modulated electrostatic and hydrogen-bonding interactions between the positively charged lysine residues at the termini of these peptides and the negatively charged polar headgroups of the PG bilayers.
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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 | 0.000 |
| 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".