The preparation, elasticity and proton/hydroxyl permeability of uniform, unilamellar vesicles of anionic phospholipids.
Item
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Title
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The preparation, elasticity and proton/hydroxyl permeability of uniform, unilamellar vesicles of anionic phospholipids.
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Identifier
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AAI8821099
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identifier
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8821099
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Creator
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Li, Wei.
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Contributor
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Adviser: Thomas H. Haines
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Date
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1988
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry
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Abstract
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A general procedure for the preparation of large unilamellar uniform vesicles of selected sizes (200-3000 nm) has been developed. The procedure consists of dissolving the lipid in organic solvent, washing with mild acid, removing the solvent, adding saline and adjusting the pH up to 10 and immediately back to 7.5. Vesicle size varies with the lipid structure, the composition of the lipid mixture and the ionic strength of the medium. The technique of dynamic light scattering has been used for measuring the elastic response of vesicle bilayer membranes to an applied osmotic pressure. The vesicles swell uniformly upon dilution. The observed change in size is not due to any change in the shape of the vesicles. The amplitude of the swelling is initially linearly proportional to the osmotic pressure difference across the bilayer. It was found that the elastic properties of the bilayer vary by a factor of ten in electrolyte media as compared to isoosmolal non-electrolyte media and that this variation appears to be dominated by the ionic strength of the media. Measurements of the proton/hydroxyl permeability across the bilayers of vesicles prepared by the pH adjustment procedure have been made. Membrane conductivity was assayed by the concentration of acridine orange into vesicles during the impression of a pH gradient of 2.5 to 3.0 units (neutral range, inside low pH) across the bilayer. The effects of the lipid head-groups, the incorporation of cholesterol into the vesicle bilayer and detergents on the membrane permeability were studied.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
