MAGAININ OLIGOMERS REVERSIBLY DISSIPATE DELTA-MU(H-OXIDASE LIPOSOMES() IN CYTOCHROME)

Magainin peptides present in the skin of Xenopus laevis and identified as antimicrobial agents are shown to decrease the membrane potential in cytochrome oxidase liposomes. They also released respiratory contro l with a third or higher order concentration dependence. Respiratory c ontrol was restored by proteolytic digestion of the added magainin. Th e amount of magainin required for half-maximal stimulation of respirat ion was proportional to lipid concentration. At appreciably higher con centrations magainins inhibited uncoupled respiration. The results are discussed in terms of a model in which most of the added magainin ads orbs as a monomer to the membranes but equilibrates with a multimeric pore that causes rather general permeability of membranes. The ensuing ion permeation dissipates membrane potential and stimulates respirati on.