Biomaterial Database

The distribution of oleic acid between chylomicron-like emulsions, phospholipid bilayers, and serum albumin. A model for fatty acid distribution between lipoproteins, membranes, and albumin. 1990

P J Spooner, and D L Gantz, and J A Hamilton, and D M Small

Department of Biophysics, Boston University School of Medicine, Housman Medical Research Center, Massachusetts 02118-2394.

In the process of lipoprotein lipolysis, masses of fatty acid are generated at the surface of the lipoprotein. The newly generated fatty acid may at least partly redistribute from the site of lipolysis to phospholipid-rich membranes and to albumin. We have studied the distribution of [1-13C]oleic acid in model systems consisting of chylomicron-like triacylglycerol-rich emulsions, unilamellar phosphatidylcholine vesicles, and bovine serum albumin. By using high resolution 13C NMR spectroscopy it was possible to distinguish fatty acid in each compartment (emulsion, vesicle, albumin) and quantitate the fatty acid distribution under various conditions of lipid compartment concentration and aqueous pH. When emulsions and vesicles were present in equivalent mass amounts, fatty acid exhibited a profound preference for the lipid bilayers. The release of oleic acid to phospholipid bilayers was presumably also a function of its high molar stoichiometry (5:1) with the albumin present. More equitable distributions of fatty acid between vesicles and emulsions were seen when higher concentrations of emulsion were used. The distribution of fatty acid between compartments was in good agreement with predictions made using the apparent ionization constant, expressed as pKapp, of 7.5 and the surface to core (phospholipid to triacylglycerol) distribution coefficient of 7.0, measured for unionized oleic acid in chylomicron particles (Spooner, P. J. R., Bennett Clark, S., Gantz, D. L., Hamilton, J. A., and Small, D. M. (1988) J. Biol. Chem. 263, 1444-1455). These results indicate that the affinities of fatty acid for phospholipid bilayer and chylomicron-like emulsion surfaces are equivalent. Redistribution of lipolytically generated fatty acid from chylomicron surface to cell membrane may simply be driven by the predominant quantity of the cell membrane surfaces.

UI	MeSH Term	Description	Entries
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D008074	Lipoproteins	Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.	Circulating Lipoproteins,Lipoprotein,Lipoproteins, Circulating
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009682	Magnetic Resonance Spectroscopy	Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).	In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D009829	Oleic Acids	A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.	Octadecenoic Acids,Acids, Octadecenoic,Acids, Oleic
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002914	Chylomicrons	A class of lipoproteins that carry dietary CHOLESTEROL and TRIGLYCERIDES from the SMALL INTESTINE to the tissues. Their density (0.93-1.006 g/ml) is the same as that of VERY-LOW-DENSITY LIPOPROTEINS.	Chylomicron
D004655	Emulsions	Colloids formed by the combination of two immiscible liquids such as oil and water. Lipid-in-water emulsions are usually liquid, like milk or lotion. Water-in-lipid emulsions tend to be creams. The formation of emulsions may be aided by amphiphatic molecules that surround one component of the system to form MICELLES.	Emulsion
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations