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Thermodynamic characterization of the association of small basic peptides with membranes containing acidic lipids

Montich, G. and Scarlata, S. and McLaughlin, S. and Lehrmann, R. and Seelig, J.. (1993) Thermodynamic characterization of the association of small basic peptides with membranes containing acidic lipids. Biochimica et biophysica acta, Vol. 1146, H. 1. pp. 17-24.

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Official URL: http://edoc.unibas.ch/dok/A5257454

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Abstract

We measured the binding of the peptide acetyl-Trp-Lys7-amide to membranes formed from mixtures of the zwitterionic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (PC) and the acidic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (PG). Direct filtration and equilibrium dialysis measurements demonstrate that binding increases sigmoidally with the mole fraction of PG as predicted from a simple Gouy-Chapman/mass action theoretical model. We used these measurements to calibrate two binding assays, one based on the increase in Trp fluorescence that occurs when the peptide binds to the membrane, the other on the quenching of Trp fluorescence that occurs when the peptide binds to membranes containing fluorescent lipids. Both fluorescence assays demonstrate that binding does not depend strongly on temperature, which suggests the enthalpy change, delta H, is small. Calorimetric measurements demonstrate this directly for the analogous basic peptide Lys5: delta H congruent to +1 kcal/mol for the binding of Lys5 to sonicated phospholipid vesicles and delta H congruent to 0 kcal/mol for its binding to large unilamellar vesicles. Thus, the decrease in the free energy that occurs when these peptides bind to the membrane is due to a positive change in the entropy of the system. Fluorescence measurements demonstrate the binding of the Trp-containing peptide to 4:1 PC/PG membranes is independent of pressure up to 2 kbar, which suggests that binding occurs without a significant change in volume.
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
Bibsysno:Link to catalogue
Publisher:Elsevier
ISSN:0006-3002
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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