Conformation of an oligopeptide in phospholipid vesicles.

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Abstract
To demonstrate a method by which the conformation of membrane proteins may be determined spectroscopically in model membranes, the structure of a hydrophobic oligopeptide, tert-butyloxycarbonylPro-Leu-Val-methyl ester in phospholipid vesicles was determined by NMR, circular dichroism (CD) and IR spectroscopy. 13C NMR and CD techniques demonstrated that the conformation of this peptide in linear hydrocarbon solutions was essentially identical to its conformation in lipid vesicles. 1H NMR and IR spectroscopy of the peptide in hydrocarbon solution provided additional high-resolution information concerning the structure of the peptide as found in the hydrophobic portion of the lipid bilayer. The conformation of this peptide in hydrophobic media differs from its structure in hydrophilic solvents, not only in bond angles and the proportion of cis/trans isomers about the X-proline bond, but also in its intermolecular associations.