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pubmed-2214911
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| recordtype |
oai_dc
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| spelling |
pubmed-22149112008-04-23 Nonelectrolyte diffusion across lipid bilayer systems Articles The permeability coefficients of a homologous series of amides from formamide through valeramide have been measured in spherical bilayers prepared by the method described by Jung. They do not depend directly on the water:ether partition coefficient which increases regularly with chain length. Instead there is a minimum at acetamide. This has been ascribed to the effect of steric hindrance on diffusion within the bilayer which increases with solute molar volume. This factor is of the same magnitude, though opposite in sign to the effect of lipid solubility, thus accounting for the minimum. The resistance to passage across the interface has been compared to the resistance to diffusion within the membrane. As the solute chain length increases the interface becomes more important, until for valeramide it comprises about 90% of the total resistance. Interface resistance is also important in urea permeation, causing urea to permeate much more slowly than an amide of comparable size, after allowance is made for the difference in the water:ether partition coefficient. Amide permeation coefficients have been compared with relative liposome permeation data measured by the rate of liposome swelling. The ratios of the two measures of permeation vary between 3 and 16 for the homologous amides. The apparent enthalpy of liposome permeation has been measured and found to be in the neighborhood of 12 kcal mol-1 essentially independent of chain length. Comparison of the bilayer permeability coefficients with those of red cells shows that red cell permeation by the lipophilic solutes resembles that of the bilayers, whereas permeation by the hydrophilic solutes differs significantly. The Rockefeller University Press 1976-01-01 /pmc/articles/PMC2214911/ /pubmed/1245835 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
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| repository_type |
Open Access Journal
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| institution_category |
Foreign Institution
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| institution |
US National Center for Biotechnology Information
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| building |
NCBI PubMed
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| collection |
Online Access
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| language |
English
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| format |
Online
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| title |
Nonelectrolyte diffusion across lipid bilayer systems
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| spellingShingle |
Nonelectrolyte diffusion across lipid bilayer systems
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| title_short |
Nonelectrolyte diffusion across lipid bilayer systems
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| title_full |
Nonelectrolyte diffusion across lipid bilayer systems
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| title_fullStr |
Nonelectrolyte diffusion across lipid bilayer systems
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| title_full_unstemmed |
Nonelectrolyte diffusion across lipid bilayer systems
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| title_sort |
nonelectrolyte diffusion across lipid bilayer systems
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| description |
The permeability coefficients of a homologous series of amides from formamide through valeramide have been measured in spherical bilayers prepared by the method described by Jung. They do not depend directly on the water:ether partition coefficient which increases regularly with chain length. Instead there is a minimum at acetamide. This has been ascribed to the effect of steric hindrance on diffusion within the bilayer which increases with solute molar volume. This factor is of the same magnitude, though opposite in sign to the effect of lipid solubility, thus accounting for the minimum. The resistance to passage across the interface has been compared to the resistance to diffusion within the membrane. As the solute chain length increases the interface becomes more important, until for valeramide it comprises about 90% of the total resistance. Interface resistance is also important in urea permeation, causing urea to permeate much more slowly than an amide of comparable size, after allowance is made for the difference in the water:ether partition coefficient. Amide permeation coefficients have been compared with relative liposome permeation data measured by the rate of liposome swelling. The ratios of the two measures of permeation vary between 3 and 16 for the homologous amides. The apparent enthalpy of liposome permeation has been measured and found to be in the neighborhood of 12 kcal mol-1 essentially independent of chain length. Comparison of the bilayer permeability coefficients with those of red cells shows that red cell permeation by the lipophilic solutes resembles that of the bilayers, whereas permeation by the hydrophilic solutes differs significantly.
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| publisher |
The Rockefeller University Press
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| publishDate |
1976
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| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2214911/
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| _version_ |
1611434919778582528
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