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Modulation of calcium phosphate formation by phosphatidate-containing anionic liposomes


Eanes, ED and Hailer, AW and Heywood, BR, Modulation of calcium phosphate formation by phosphatidate-containing anionic liposomes, Calcified Tissue International, 43, (4) pp. 226-234. ISSN 0171-967X (1988) [Refereed Article]

Copyright Statement

Copyright 1988 Springer-Verlag New York Inc.

DOI: doi:10.1007/BF02555139


Liposomes prepared from 7∶2∶1 molar mixtures of phosphatidylcholine, dicetyl phosphate, and cholesterol to which 120 mole % dioleoylphosphatidic acid (DOPA) was added were used to examine the effect of membrane-bound monoester phosphatidate phosphate anions on calcium phosphate formation in aqueous solutions at 22C, pH 7.4, and 240 mOsm. Results showed that up to 20 mole % DOPA in the liposomal envelope did not initiate mineralization in solutions made meta-stable with 2.25 mM CaCl2 and 1.50 mM KH2PO4. Results also revealed that precipitation induced in metastable solutions by the seeding action of intraliposomally formed mineral was measurably reduced with as little as 1 mole % DOPA and completely suppressed with 5 mole % DOPA. In contrast, 10 mole % concentrations of diester phosphate lipids either had no effect on extraliposomal precipitation (e.g., phosphatidylglycerol and phosphatidylinositol) or, as reported previously for phosphatidylserine, only partially reduced the amount of precipitate formed. Transmission electron microscopical analysis suggests that DOPA-containing lipid bilayers adhering to the seed crystals inhibited extraliposomal mineralization by encapsulating the crystals within the liposomes and/or by blocking potential growth sites on the crystal faces. The polar head group of DOPA, being more negatively charged and sterically less encumbered than diester phosphate ligands, most probably was responsible for this adherence of the lipid bilayers to the crystal surfaces.

Item Details

Item Type:Refereed Article
Keywords:apatite, calcium phosphates, liposomes, matrix vesicles, phosphatidic acid
Research Division:Biomedical and Clinical Sciences
Research Group:Medical biochemistry and metabolomics
Research Field:Medical biochemistry - inorganic elements and compounds
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Heywood, BR (Professor Brigid Heywood)
ID Code:104349
Year Published:1988
Web of Science® Times Cited:11
Deposited By:Research Division
Deposited On:2015-11-10
Last Modified:2015-12-18

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