Circular dichroism studies on a synthetic peptide corresponding to the membrane-spanning region of vesicular stomatitis virus G protein and its fatty acyl derivative

Abstract

The conformations of synthetic peptides Lys-Phe-Phe-Phe-Ile-Ile-Gly-Leu-Ile-Ile-Gly-Leu-Phe-OCH₃ and Lys-(-palmitoyl)-Phe-Phe-Phe-Ile-Ile-Gly-Leu-Ile-Ile-Gly-Leu-Phe-OCH₃, which constitute a part of the membrane-spanning region of the vesicular stomatitis virus G protein, have been studied by circular dichroism (CD) spectroscopy. Secondary structural features are observed for both peptides in trifluoroethanol, methanol, aqueous mixtures of trifluoroethanol and methanol and in a micellar environment. In trifluoroethanol, the CD spectra indicate the presence of a helical conformation, whereas in aqueous mixtures of organic solvents, both helical and β-conformations are observed. While fatty acid acylation does not directly modulate peptide conformation, it promotes self-association of the acylated peptide and association with micelles. In a micellar environment, the acylated peptide adopts an a-helical conformation.