Study of vesicle leakage induced by melittin.
Biochim Biophys Acta
; 1235(2): 452-60, 1995 May 04.
Article
em En
| MEDLINE
| ID: mdl-7756355
ABSTRACT
The leakage induced by melittin, a membrane-perturbing amphipathic peptide, from large unilamellar 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) vesicles was studied using calcein as fluorescent marker. The extent of leakage has been found to be regulated by the melittin/lipid molar ratio. Melittin leads to the complete release of trapped calcein from some vesicles. This all-or-none mechanism leads to the co-existence of two different vesicle populations the 'empty' and the intact one. Intervesicular migration of melittin was not observed. The results reveal a specific targeting of the lysed vesicles by melittin. The presence of negatively charged lipids (unprotonated palmitic acid or 1-palmitoyl-2-oleoylphosphatidylglycerol) in the neutral POPC matrix inhibits the lytic power of melittin; this inhibition increases with increasing surface charge density. It is proposed that the anchorage of the peptide on the charged surface prevents the formation of defects allowing leakage. A statistical model based on a random distribution of the peptide molecules on the vesicles is proposed to describe the release induced by melittin. It is proposed that about 250 melittin molecules per vesicle are required to affect the bilayer permeability and to empty a vesicle of its content. This large number suggests that leakage is more likely due to collective membrane perturbation by the peptide rather than to the formation of a well-defined pore.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Lipossomos
/
Meliteno
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Ano de publicação:
1995
Tipo de documento:
Article