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Effect of peptide length on the interaction between consensus peptides and DOPC/DOPA bilayers.
Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy.
2006 (English)In: Langmuir, ISSN 0743-7463, Vol. 22, no 11, 5042-50 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2006. Vol. 22, no 11, 5042-50 p.
URN: urn:nbn:se:uu:diva-81959PubMedID: 16700592OAI: oai:DiVA.org:uu-81959DiVA: diva2:109874
Available from: 2006-09-06 Created: 2006-09-06 Last updated: 2011-01-11
In thesis
1. Interaction Between Antimicrobial Peptides and Phospholipid Membranes: Effects of Peptide Length and Composition
Open this publication in new window or tab >>Interaction Between Antimicrobial Peptides and Phospholipid Membranes: Effects of Peptide Length and Composition
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Due to increasing problems with bacterial resistance development, there is a growing need for identifying new types of antibiotics. Antimicrobial peptides constitute an interesting group of substances for this purpose, since they are believed to act mainly by disrupting the bacterial membrane, which is a fast and non-specific mechanism. In order to understand the details on this action simplified phospholipid model membranes based on liposomes, monolayers and bilayers, were employed in this thesis.

By in situ ellipsometry studies on supported lipid bilayers in combination with leakage from liposomes it was found that peptide-induced membrane rupture to a great extent is related to peptide adsorption. The peptide activity and mechanism of action is highly dependent on peptide properties such as length, topology, charge, and hydrophobicity. Electrostatic interactions are crucial for peptide adsorption, whereas α-helix formation is of less importance, demonstrated by the dominating peptide conformation being random coil both in absence and presence of membranes, as investigated by circular dichroism. Comparable effects were observed in both mono- and bilayer systems, showing that formation of transmembrane structures is no prerequisite for membrane rupture by complement-derived peptides. Electrochemical studies on these peptides further demonstrated that hydrophobic interactions facilitate peptide penetration into the membrane, causing defects in close proximity to the peptides, while strong electrostatic interactions arrest the peptide in the headgroup region. Increasing the peptide hydrophobicity, by e.g., tryptophan end-tagging, also increases salt resistance.

Good correlations were found between model membrane investigations and antibacterial activity towards both Gram-negative and Gram-positive bacteria, showing that membrane rupture is a key mechanism of action for the peptides investigated. In addition, for all peptides investigated cell toxicity is low.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 61 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 101
Adsorption, antibacterial, antimicrobial peptide, bilayer, ellipsometry, electrochemistry, electrostatic interactions, hydrophobicity, liposome, membrane, monolayer, phospholipid, secondary structure, supported bilayer.
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutical Physical Chemistry
urn:nbn:se:uu:diva-101989 (URN)978-91-554-7540-6 (ISBN)
Public defence
2009-06-12, B42, Biomedical Center, BMC, Husargatan 3, Uppsala, 13:15 (English)
Available from: 2009-05-18 Created: 2009-04-29 Last updated: 2009-05-18Bibliographically approved

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Ringstad, LovisaMalmsten, Martin
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