Detergent-like action of the antibiotic peptide surfactin on lipid membranes

Heerklotz, H. and Seelig, J.. (2001) Detergent-like action of the antibiotic peptide surfactin on lipid membranes. Biophysical journal, Vol. 81, H. 3. pp. 1547-1554.

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Official URL: http://edoc.unibas.ch/dok/A5257405

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Surfactin is a bacterial lipopeptide with powerful surfactant-like properties. High-sensitivity isothermal titration calorimetry was used to study the self association and membrane partitioning of surfactin. The critical micellar concentration (CMC), was 7.5 microM, the heat of micellization was endothermic with DeltaH(w--<m)(Su) = +4.0 kcal/mol, and the free energy of micellization DeltaG(O,w--<m)(Su) = -9.3 kcal/mol (25 degrees C; 100 mM NaCl; 10 mM TRIS, 1 mM EDTA; pH 8.5). The specific heat capacity of micellization was deduced from temperature dependence of DeltaH(w--<m)(Su) as DeltaC(w--<m)(P) = -250 +/- 10 cal/(mol.K). The data can be explained by combining the hydrophobicity of the fatty acyl chain with that of the hydrophobic amino acids. The membrane partition equilibrium was studied using small (30 nm) and large (100 nm) unilamellar POPC vesicles. At 25 degrees C, the partition coefficient, K, was (2.2 +/- 0.2) x 10(4) M(-1) for large vesicles leading to a free energy of DeltaG(O, w--<b)(Su) = -8.3 kcal/mol. The partition enthalpy was again endothermic, with DeltaH(w--<b)(Su) = 9 +/- 1 kcal/mol. The strong preference of surfactin for micelle formation over membrane insertion explains the high membrane-destabilizing activity of the peptide. For surfactin and a variety of non-ionic detergents, the surfactant-to-lipid ratio, inducing membrane solubilization, R(sat)(b), can be predicted by the simple relationship R(sat)(b) approximately K. CMC.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biophysical Chemistry (Seelig J)
UniBasel Contributors:Seelig, Joachim
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Biophysical Society
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:19
Deposited On:22 Mar 2012 13:18

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