Anion binding to neutral and positively charged lipid membranes

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Anion binding to neutral and positively charged lipid membranes

JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)

ID	153067
Author(s)	Macdonald, P M; Seelig, J
Author(s) at UniBasel	Seelig, Joachim
Year	1988
Title	Anion binding to neutral and positively charged lipid membranes
Journal	Biochemistry
Volume	27
Number	18
Pages / Article-Number	6769-75
Keywords	Anions; Binding Sites; Electrochemistry; Kinetics; *Lipid Bilayers; Magnetic Resonance Spectroscopy; Phosphatidylcholines; Quaternary Ammonium Compounds; Thiocyanates
Abstract	Aqueous anion binding to bilayer membranes consisting of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) was investigated by using deuterium and phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy. Only those anions that exhibit chaotropic properties showed significant binding to POPC membranes. A detailed investigation of thiocyanate binding to neutral POPC and to positively charged mixed POPC/dihexadecyldimethylammonium bromide (DHDMAB) (8:2 mol/mol) membranes revealed changes in the 2H NMR quadrupole splittings from POPC specifically deuteriated at either the alpha-segment or the beta-segment of the choline head group which were consistent with a progressive accumulation of excess negative charge at the membrane surface with increasing SCN- concentration. Both the 2H and 31P NMR spectra indicated the presence of fluid lipids in a bilayer configuration up to at least 1.0 M NaSCN with no indication of any phase separation of lipid domains. Calibration of the relationship between the change in the 2H NMR quadrupole splitting and the amount of SCN- binding provided thiocyanate binding isotherms. At a given SCN- concentration the positively charged membranes bound levels of SCN- 3 times that of the neutral membranes. The binding isotherms were analyzed by considering both the electrostatic and the chemical equilibrium contributions to SCN- binding. Electrostatic considerations were accounted for by using the Gouy-Chapman theory. For 100% POPC membranes as well as for mixed POPC/DHDMAB (8:2 mol/mol) membranes the thiocyanate binding up to concentrations of 100 mM was characterized by a partition equilibrium with an association constant of K approximately 1.4 +/- 0.3 M-1.(ABSTRACT TRUNCATED AT 250 WORDS)
Publisher	American Chemical Society
ISSN/ISBN	0006-2960
edoc-URL	http://edoc.unibas.ch/dok/A5257486
Full Text on edoc	No
Digital Object Identifier DOI	10.1021/bi00418a019
PubMed ID	http://www.ncbi.nlm.nih.gov/pubmed/3196682
ISI-Number	WOS:A1988Q103000019
Document type (ISI)	Journal Article

20/04/2024

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