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Persistent URL
http://purl.org/net/epubs/work/64481
Record Status
Checked
Record Id
64481
Title
Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-a-dimyristoyl phosphatidylcholine
Contributors
H Kell
,
JF Holzwarth
,
C Boettcher
,
RK Heenan (STFC Rutherford Appleton Lab.)
,
J Vater
Abstract
To understand the biological action of surfactin from Bacillus subtilis we investigated its effects on the phase transition of L-?-dimyristoyl phosphatidylcholine (DMPC)-vesicles from the crystalline to the fluid state using differential scanning calorimetry; light scattering; small angle neutron scattering and cryo-electron microscopy. DSC-thermograms revealed two phase transition peaks. Light scattering profiles showed two branches with characteristic hysteresis phenomena. With both techniques the same values of the phase transition temperatures Tm1 and Tm2 of 23.5 and 23 °C were obtained indicating two forms of DMPC–surfactin aggregates which could be visualized by cryo-electron microscopy. Until 4 mol% surfactin the vesicular form predominated, but was accompanied by bilayered membrane fragments by increasing the biosurfactant concentrations. At surfactin concentrations higher than 15 mol% smaller DMPC–surfactin micelles of ellipsoidal conformation were formed, as demonstrated by small angle neutron scattering. In addition, by “Poor Man's” temperature-jump-relaxation spectroscopy slow transients in the phase transition of vesicular DMPC–surfactin aggregates with relaxation times of 20–30 s were detected which presumably indicate the slow dissipation of intermediate lipid-and surfactin domains formed after the main phase transition on the way to the fluid state. This process is accelerated by surfactin.
Organisation
ISIS
,
ISIS-LOQ
,
STFC
Keywords
Funding Information
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Language
English (EN)
Type
Details
URI(s)
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Year
Journal Article
Biophys Chem
128, no. 2-3 (2007): 114-124.
doi:10.1016/j.bpc.2007.03.005
2007
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