Exchange of monooleoylphosphatidylcholine with single egg phosphatidylcholine vesicle membranes. 1996

D V Zhelev
Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708-0300, USA. dvzh@acpub.duke.edu

In a previous paper we described the experiments and the framework of a model for the exchange of monooleoylphosphatidylcholine with a single egg phosphatidylcholine membrane. In the present paper a model is presented that relates the experimentally measured apparent characteristics of the overall kinetics of lysolipid exchange to the true rates of lysolipid exchange and interbilayer transfer. It is shown that the adsorption of the lysolipid follows two pathways: one through the adsorption of lipid monomers and other through the fusion of micelles. The desorption of lysolipid follows a single pathway, namely, the desorption of monomers. The overall rate of fast desorption under convective flow conditions gives the true rate of monomer desorption from the outer membrane monolayer. The overall rate of both slow lysolipid uptake and slow desorption gives the rate of interbilayer transfer. Because of the uneven distribution of lysolipid between the two monolayers during its uptake, one of the membrane monolayers is apparently extended relative to the other. This relative extension of one of the monolayers induces a monolayer tension. The induced monolayer tension can increase up to 7 mN.m-1, when most of the intercalated lysolipid only partitions into the monolayer facing the lysolipid solution. This value is similar to the measured value for the critical monolayer tension of membrane failure, which is on the order of 5 mN.m-1. The similarity of the magnitudes of the induced monolayer tension during monooleoylphosphatidylcholine exchange and the monolayer tension of membrane failure suggests that the interbilayer lipid transfer may be affected by the formation of short living membrane defects. Furthermore, the pH-induced interbilayer exchange of phosphatidylglycerol is considered. In this case, it is shown that the rate of interbilayer transfer is a function of the phosphatidylglycerol concentration in the membrane.

UI MeSH Term Description Entries
D007364 Intercalating Agents Agents that are capable of inserting themselves between the successive bases in DNA, thus kinking, uncoiling or otherwise deforming it and therefore preventing its proper functioning. They are used in the study of DNA. Intercalating Agent,Intercalating Ligand,Intercalative Compound,Intercalator,Intercalators,Intercalating Ligands,Intercalative Compounds,Agent, Intercalating,Agents, Intercalating,Compound, Intercalative,Compounds, Intercalative,Ligand, Intercalating,Ligands, Intercalating
D007700 Kinetics The rate dynamics in chemical or physical systems.
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
D008244 Lysophosphatidylcholines Derivatives of PHOSPHATIDYLCHOLINES obtained by their partial hydrolysis which removes one of the fatty acid moieties. Lysolecithin,Lysolecithins,Lysophosphatidylcholine
D008563 Membrane Lipids Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation. Cell Membrane Lipid,Cell Membrane Lipids,Membrane Lipid,Lipid, Cell Membrane,Lipid, Membrane,Lipids, Cell Membrane,Lipids, Membrane,Membrane Lipid, Cell,Membrane Lipids, Cell
D008567 Membranes, Artificial Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION. Artificial Membranes,Artificial Membrane,Membrane, Artificial
D008956 Models, Chemical Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment. Chemical Models,Chemical Model,Model, Chemical
D010063 Ovum A mature haploid female germ cell extruded from the OVARY at OVULATION. Egg,Egg, Unfertilized,Ova,Eggs, Unfertilized,Unfertilized Egg,Unfertilized Eggs
D010713 Phosphatidylcholines Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a CHOLINE moiety. Choline Phosphoglycerides,Choline Glycerophospholipids,Phosphatidyl Choline,Phosphatidyl Cholines,Phosphatidylcholine,Choline, Phosphatidyl,Cholines, Phosphatidyl,Glycerophospholipids, Choline,Phosphoglycerides, Choline
D010715 Phosphatidylglycerols A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis. Glycerol Phosphoglycerides,Monophosphatidylglycerols,Phosphatidylglycerol,Phosphatidyl Glycerol,Glycerol, Phosphatidyl,Phosphoglycerides, Glycerol
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