A FOURIER-TRANSFORM INFRARED SPECTROSCOPIC INVESTIGATION OF HYDROPHOBIC PEPTIDES IN LIPID ENVIRONMENT - A MONOLAYER STUDY

The properties of tripeptides Ala-Ala-Tyr and Leu-Leu-Tyr have been in vestigated in monolayers by resolution enhanced Fourier transform infr ared spetroscopy (FTIR). Interaction with an acidic phospholipid (DPPA ) in the mixed monolayer results in changes in the backbone amide grou ps, whereas neutral phospholipid has no effect on the peptides. From t he positions of the amide I bands of the peptides, it can be inferred that the groups are in non-ordered conformation. These observations ha ve important implications for the mechanisms of peptide hormone-recept or interactions and particularly for the role of membrane lipid phase as a biologically important modifier of the hormone conformation.