MONOLAYER FORMATION AND MOLECULAR-ORIENTATION OF VARIOUS HELICAL PEPTIDES AT THE AIR WATER INTERFACE/

Ten binds of helical peptides were synthesized to study interaction be tween helices in the peptide monolayer formed at the air/water interfa ce. Five of those have a repeating sequence of Ala-Aib and different e nd groups, other two a repeating sequence of Lys(Z)-Aib, and the rest a repeating sequence of Leu-Aib. All of the peptides take helical conf ormation in ethanol as confirmed by CD spectroscopy. The surface press ure-area isotherms of the peptide monolayers showed an inflection at t he surface area corresponding to the cross section along the helix axi s, where the monolayers are considered to collapse. The monolayers wer e transferred onto substrates and subjected to IR transmission and ref lection absorption spectroscopy. By comparison of amide I and II absor bances, the peptides seemed to Lie on the substrates. It was concluded that the peptides in the monolayer orient their helical axis parallel to the air/water interface.