In vitro interaction of opioid peptides with phospholipids. Formation and characterization of complexes

Interaction of Leu- and Met-enkephalin with phosphatidylserine has been studied by chromatographic and spectrophotometric techniques. The main results of our investigation may be summarized as follows: i) Both enkephalins bind to phosphatidylserine; ii) no difference between the two enkephalins is noticeable; and iii) with both peptides the binding phenomenon leads to the formation of two complexes with a definite stoichiometry which are sterically much smaller than the original vesicles. On the basis of the submitted data, a tentative model of the newly formed complexes is provided.