Magainin oligomers reversibly dissipate delta microH+ in cytochrome oxidase liposomes.
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 control with a third or higher order concentration dependence. Respiratory control was restored by proteolytic digestion of the added magainin. The amount of magainin required for half-maximal stimulation of respiration was proportional to lipid concentration. At appreciably higher concentrations magainins inhibited uncoupled respiration. The results are discussed in terms of a model in which most of the added magainin adsorbs 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 respiration.
Juretić
D
D
Section on Membrane Enzymology, National Heart, Lung and Blood Institute, National Institutes of Heath, Bethesda, Maryland 20892.
Hendler
R W
RW
Kamp
F
F
Caughey
W S
WS
Zasloff
M
M
Westerhoff
H V
HV
D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D002463:Cell Membrane Permeability / Q000187:drug effects; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000378:metabolism*; D046911:Macromolecular Substances; D054806:Magainins; D008555:Melitten / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D012867:Skin / Q000737:chemistry; D029867:Xenopus Proteins; D014982:Xenopus laevis
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D008081:Liposomes; D046911:Macromolecular Substances; D054806:Magainins; D029867:Xenopus Proteins; C053301:magainin 2 peptide, Xenopus; D008555:Melitten; D003576:Electron Transport Complex IV