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Partitioning of local anesthetics into membranes : surface charge effects monitored by the phospholipid head-group

Seelig, A. and Allegrini, P. R. and Seelig, J.. (1988) Partitioning of local anesthetics into membranes : surface charge effects monitored by the phospholipid head-group. Biochimica et biophysica acta, Vol. 939, H. 2. S. 267-276.

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Official URL: http://edoc.unibas.ch/dok/A5258493

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Abstract

The binding of the charged form of two local anesthetics, dibucaine and etidocaine, to bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) was measured simultaneously with ultraviolet spectroscopy and deuterium magnetic resonance. Because of their amphiphilic molecular structure, both drugs intercalate between the lipid molecules, increasing the surface area and imparting a positive electric charge onto the membrane. The ultraviolet (UV) binding isotherms were therefore analyzed in terms of a model which specifically took into account the bilayer expansion as well as the charge-induced concentration variations near the membrane surface. By formulating a quantitative expression for the change in surface area upon drug intercalation and combining it with the Gouy-Chapman theory, the binding of charged dibucaine and etidocaine to the lipid membrane was best described by a partition equilibrium, with surface partition coefficients of 660 +/- 80 M-1 and 11 +/- 2 M-1 for dibucaine and etidocaine, respectively (pH 5.5, 0.1 M NaCl/50 mM buffer). Deuterium magnetic resonance demonstrated further that the binding of drug changed the head-group conformation of the lipid molecules. Invoking the intercalation model, a linear variation of the deuterium quadrupole splittings of the choline segments with the surface charge density was observed, suggesting that the phosphocholine head-group may act as a 'molecular electrometer' with respect to surface charges.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biophysical Chemistry (Seelig A)
05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biophysical Chemistry (Seelig J)
UniBasel Contributors:Seelig, Joachim and Seelig-Löffler, Anna
Item Type:Article, refereed
Bibsysno:Link to catalogue
Publisher:Elsevier
ISSN:0006-3002
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2012 06:48
Deposited On:22 Mar 2012 13:20

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