Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol
We used an automated Langmuir-Pockels surface balance to characterize the air–water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,...
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| Format: | Article |
| Language: | English |
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Elsevier
2000-06-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520320423 |
| _version_ | 1818731650401435648 |
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| author | John M. Kauffman Philip W. Westerman Martin C. Carey |
| author_facet | John M. Kauffman Philip W. Westerman Martin C. Carey |
| author_sort | John M. Kauffman |
| collection | DOAJ |
| description | We used an automated Langmuir-Pockels surface balance to characterize the air–water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphocholine (POPC). Pressure–area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22–26 Å2/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH. In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 Å2/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydroxycholesterols expanded POPC monolayers at molar ratios <30%, but induced condensation with higher ratios, suggesting that OH-acyl chain (POPC) repulsion is superceded at higher mole fractions by lateral phase separation and intersteroidal H-bonding.These studies predict that fluorocholesterols should exhibit intramembrane spatial occupancy nearly identical to CH, whereas nucleus and especially side chain hydroxycholesterols will perturb membrane lipid packing notably. |
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| format | Article |
| id | doaj.art-f1782d1d37a64bd2b5052af7edcf43c5 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-17T23:21:03Z |
| publishDate | 2000-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-f1782d1d37a64bd2b5052af7edcf43c52022-12-21T21:28:54ZengElsevierJournal of Lipid Research0022-22752000-06-014169911003Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterolJohn M. Kauffman0Philip W. Westerman1Martin C. Carey2Department of Medicine, Harvard Medical School, Harvard Digestive Diseases Center, and Division of Gastroenterology, Brigham and Women's Hospital, Boston, MA 02115Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities' College of Medicine, Rootstown, OH 44272To whom correspondence should be addressed.; Department of Medicine, Harvard Medical School, Harvard Digestive Diseases Center, and Division of Gastroenterology, Brigham and Women's Hospital, Boston, MA 02115We used an automated Langmuir-Pockels surface balance to characterize the air–water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphocholine (POPC). Pressure–area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22–26 Å2/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH. In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 Å2/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydroxycholesterols expanded POPC monolayers at molar ratios <30%, but induced condensation with higher ratios, suggesting that OH-acyl chain (POPC) repulsion is superceded at higher mole fractions by lateral phase separation and intersteroidal H-bonding.These studies predict that fluorocholesterols should exhibit intramembrane spatial occupancy nearly identical to CH, whereas nucleus and especially side chain hydroxycholesterols will perturb membrane lipid packing notably.http://www.sciencedirect.com/science/article/pii/S0022227520320423phosphatidylcholinesurface potentialcondensationisothermorientationsurface balance |
| spellingShingle | John M. Kauffman Philip W. Westerman Martin C. Carey Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol Journal of Lipid Research phosphatidylcholine surface potential condensation isotherm orientation surface balance |
| title | Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol |
| title_full | Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol |
| title_fullStr | Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol |
| title_full_unstemmed | Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol |
| title_short | Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol |
| title_sort | fluorocholesterols in contrast to hydroxycholesterols exhibit interfacial properties similar to cholesterol |
| topic | phosphatidylcholine surface potential condensation isotherm orientation surface balance |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520320423 |
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