Energetics and partition of two cecropin-melittin hybrid peptides to model membranes of different composition

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Margarida Bastos (Author) FCUP; Guangyue Bai (Author) Other; Paula Gomes (Author) FCUP; David Andreu (Author) Other; Erik Goormaghtigh (Author) Other; Manuel Prieo (Author) Other

Journal

Title: Biophysical Journal

Vol. 94

Pages: 2128-2141

ISSN: 0006-3495

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 40 Citations

Scopus - 42 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-004-0W3

DOI: 10.1529/biophysj.107.119032

Abstract (EN): 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.

Language: English

Type (Professor's evaluation): Scientific