Comparative interaction of α-helical and β-sheet amphiphilic isopeptides with phospholipid monolayers

• Published in: Biopolymers 2001-07, Vol.59 (1), p.1-10
• Main Authors: Maget-Dana, Régine, Lelièvre, Dominique
• Format: Article
• Language: English
• Subjects: (Leu-Lys)8; (Leu-Lys-Lys-Leu)4; air/water interface; Dimyristoylphosphatidylcholine - metabolism; L-α-dimyristoyl phosphatidylcholine (DMPC); Membranes, Artificial; mixed peptide/lipid monolayers; penetration into lipid monolayers; Peptides - chemical synthesis; Peptides - chemistry; Peptides - metabolism; Protein Binding; Protein Structure, Secondary; sequential amphiphilic isopeptides; Surface-Active Agents - chemistry; Surface-Active Agents - metabolism; α-helical and β-sheet conformations
• ISSN: 0006-3525; 1097-0282
• DOI: 10.1002/1097-0282(200107)59:1<1::AID-BIP1000>3.0.CO;2-#

The two sequential amphiphilic peptide isomers, (Leu–Lys–Lys–Leu)4 and (Leu–Lys)8, were chosen as models for α‐helical and β‐sheet peptides, respectively. In order to evaluate the contribution of the secondary structure of a peptide to its penetration into cellular membranes, interactions of these isopeptides with L‐α‐dimyristoyl phosphatidylcholine (DMPC) monolayers were studied. Both isopeptides penetrate into DMPC monolayers up to an exclusion pressure of ∼27 mN/m, but a discontinuity is observed in the penetration profile of the α‐helical (LKKL)4. The main parameters extracted from the compression isotherms of the mixed peptide/DMPC monolayers—namely, transition pressure, mean area, elasticity modulus, and energy of mixing—were analyzed. These analyses indicate that the α‐helical isomer interacts strongly with DMPC by forming a 1:32 (LKKL)4–DMPC complex. When engaged in this complex, (LKKL)4 behaves as an hydrophobic helix and has a tendency to become vertically oriented in the course of the compression process. The β‐sheet (LK)8 interacts more weakly with DMPC and no complex can be detected. © 2001 John Wiley & Sons, Inc. Biopolymers 59: 1–10, 2001