A model for cation adsorption in closed systems: Application to calcium binding to phospholipid vesicles

Shlomo Nir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

A model for cation adsorption to negatively charged surfaces is developed and applied to the analysis of recent results on Ca2+ binding to phosphadidylserine (PS), phosphadylcholine (PC)/PS, and phosphatidylethanolamine (PE)/PS vesicles. The model combines electrostatics with specific binding and considers explicitly cation depletion from solution due to adsorption. Effect of concentration of surface sites on cation adsorption is elucidated for various combinations of cation concentrations and binding coefficients. Binding of Ca2+ to PS in pure and mixed vesicles which are intact and disperse is well accounted for by employing intrinsic binding coefficients whose values are KCa = 30 M-1, KNa = 0.8 M-1, and KMg = 20 M-1. Vesicles undergoing aggregation and fusion exhibit enhanced affinity of binding of Ca2+ to PS. It is proposed that the enhanced binding is associated with vesicle fusion.

Original languageEnglish
Pages (from-to)313-321
Number of pages9
JournalJournal of Colloid and Interface Science
Volume102
Issue number2
DOIs
StatePublished - Dec 1984

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