A hydrophobic peptide, Boc-(Ala-Aib)8-OMe (BA16M), and its end-modified derivatives were synthesized, and the pressure-area (π-A) isotherms of the peptides spread at the air/water interface were studied from the viewpoint of interhelix interactions. All π-A isotherms of the synthetic peptides showed an inflection and weak irregular bumping at a surface areas of about 240 and 230 Å2/molecule, respectively, indicating that the helix axis of the peptide is oriented parallel to the interface. A small mound was observed at around 300 Å2/molecule in the π-a isotherm of BA16M, which was ascribed to the phase transition from a liquid to a solid state. The monolayer of an equimolar mixture of the peptides having an opposite kind of charge in the end group underwent the phase transition in the π-A isotherm, which was not observed with one of the two peptides. The electrostatic interaction between the end groups should stabilize the molecular packing at the interface.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces