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Author(s): Margarida Bastos
Guangyue Bai
Paula Gomes
David Andreu
Erik Goormaghtigh
Manuel Prieo
Title: Energetics and partition of two cecropin-melittin hybrid peptides to model membranes of different composition
Issue Date: 2008
Abstract: The energetics and partition of two hybrid peptides of cecropin A and melittin (CA(1-8)M(1-18) and CA(1-7)M(2-9)) with liposomes of different composition were studied by time-resolved fluorescence spectroscopy, isothermal titration calorimetry, and surface plasmon resonance. The study was carried out with large unilamellar vesicles of three different lipid compositions: 1,2-dimyristoil-sn-glycero-3-phosphocholine (DMPC), 1,2-dimyristoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DMPG), and a 3:1 binary mixture of DMPC/DMPG in a wide range of peptide/lipid ratios. The results are compatible with a model involving a strong electrostatic surface interaction between the peptides and the negatively charged liposomes, giving rise to aggregation and precipitation. A correlation is observed in the calorimetric experiments between the observed events and charge neutralization for negatively charged and mixed membranes. In the case of zwitterionic membranes, a very interesting case study was obtained with the smaller peptide, CA(1-7)M(2-9). The calorimetric results obtained for this peptide in a large range of peptide/lipid ratios can be interpreted on the basis of an initial and progressive surface coverage until a threshold concentration, where the orientation changes from parallel to perpendicular to the membrane, followed by pore formation and eventually membrane disruption. The importance of negatively charged lipids on the discrimination between bacterial and eukaryotic membranes is emphasized.
Subject: Ciências biológicas
Biological sciences
Scientific areas: Ciências exactas e naturais::Ciências biológicas
Natural sciences::Biological sciences
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:FCUP - Artigo em Revista Científica Internacional

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