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Adsorption of Ca2+ and La3+ to bilayer membranes : measurement of the adsorption enthalpy and binding constant with titration calorimetry
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 153026
Author(s) Lehrmann, R; Seelig, J
Author(s) at UniBasel Seelig, Joachim
Year 1994
Title Adsorption of Ca2+ and La3+ to bilayer membranes : measurement of the adsorption enthalpy and binding constant with titration calorimetry
Journal Biochimica et biophysica acta
Volume 1189
Number 1
Pages / Article-Number 89-95
Keywords ADSORPTION ENTHALPY, BILAYER MEMBRANE, BINDING CONSTANT, TITRATION CALORIMETRY, CALCIUM ION, LANTHANUM ION
Abstract The adsorption of Ca2+ and La3+ ions to the surface of lipid bilayer membranes was studied with high sensitivity titration calorimetry. Ca2+ adsorbs to mixed phosphatidylcholine/phosphatidylglycerol membranes with a reaction enthalpy of delta H approximately 0.1-0.2 kcal/mol. La3+ binds to sonified phosphatidylcholine vesicles with a reaction enthalpy of delta H approximately +1.8 kcal/mol. Adsorption of La3+ to phosphatidylcholine bilayers imparts a net positive charge to the membrane surface which makes the binding of further La3+ increasingly more difficult. From the decreasing amplitudes in the calorimetric titration experiment a La3+ adsorption constant of K approximately (4.1 +/- 1.1) x 10(3) M-1 was evaluated. Electrostatic effects were corrected for by means of the Gouy-Chapman theory. The adsorption constant of Ca2+ was determined previously as K approximately 10-20 M-1 using the same binding model. Since the reaction enthalpies of Ca2+ and La3+ adsorption are endothermic, the adsorption of both metal ions to the membrane surface is driven by a distinct change in entropy.
Publisher Elsevier
ISSN/ISBN 0006-3002
edoc-URL http://edoc.unibas.ch/dok/A5257447
Full Text on edoc No
Digital Object Identifier DOI 10.1016/0005-2736(94)90284-4
PubMed ID http://www.ncbi.nlm.nih.gov/pubmed/8305464
ISI-Number WOS:A1994MX86400013
Document type (ISI) Journal Article
 
   

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