Journal ArticleDOI
Effects of replacement of a double bond by a cyclopropane ring in phosphatidylethanolamines: a 2H NMR study of phase transitions and molecular organization.
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Observations are consistent with the poor packing ability of mixed saturated and cyclopropane-containing chains due to the bulky substituent effect.Abstract:
The thermotropic behavior and molecular properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-dihydrosterculoyl-sn-glycero-3-phosphoethanolamine (PDSPE) have been investigated by 2H NMR spectroscopy using samples selectively labeled at the 5'-, 9'-, 10'-, and 16'-positions of the sn-2 chains. Comparison with the corresponding phosphocholine analogues (POPC and PDSPC), obtained as intermediate synthetic products, was used to monitor the role of the polar head group. Replacement of the choline moiety by ethanolamine increased the gel to liquid-crystal transition temperature by 10-32 degrees C and led to a significantly higher ordering of the fatty acyl chains in the liquid-crystalline bilayer state. The lateral compression effect, due to the smaller area per polar head group in PE, results in a bilayer to hexagonal phase transition at elevated temperatures. The effects on both PC and PE due to replacement of the olefinic group by a cyclopropane unit are similar. A decrease in the temperature of the gel to liquid-crystal phase transition, Tc, is observed upon introduction of a cyclopropane ring; it goes from 26 degrees C in POPE to approximately 10 degrees C in PDSPE. In addition, a very significant broadening of the transition profile is observed. These observations are consistent with the poor packing ability of mixed saturated and cyclopropane-containing chains due to the bulky substituent effect. The temperature of the bilayer-hexagonal phase transition of PE samples was decreased by 15-20 degrees C on replacement of oleoyl chains by dihydrosterculoyl chains at the sn-2 position.(ABSTRACT TRUNCATED AT 250 WORDS)read more
Citations
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Journal ArticleDOI
Phases and phase transitions of the phosphatidylcholines
Rumiana Koynova,Martin Caffrey +1 more
TL;DR: A review of the data subset referring to phosphatidylcholine phase behavior reflecting changes in lipid chain length, unsaturation, asymmetry and branching, type of chain-glycerol linkage (ester, ether, amide), and position of chain attachment to the glycerol backbone are presented.
Journal ArticleDOI
Structure of the inverted hexagonal (HII) phase, and non-lamellar phase transitions of lipids.
TL;DR: The chiral stationary phase transitions of non-lamellar phase transitions are studied to show the role of chiral reprograming in the evolution of phase-by-phase chiral phase transitions.
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Structure of Fully Hydrated Fluid Phase Lipid Bilayers with Monounsaturated Chains
TL;DR: The results suggest that lipids with one monounsaturated chain have quantitative bilayer structures closer tolipids with two monounSaturated chains than to lipid with two completely saturated chains.
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Mycolic acids: structure, biosynthesis and physiological functions.
Clifton E. Barry,Richard Edward Lee,Khisimusi Mdluli,Andrea E Sampson,Benjamin G. Schroeder,Richard A. Slayden,Ying Yuan +6 more
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Cyclopropane ring formation in membrane lipids of bacteria.
Dennis W. Grogan,John E. Cronan +1 more
TL;DR: Manipulation of the CFA synthase of Escherichia coli by genetic methods has nevertheless provided valuable insight into the physiology of CFA formation and identified the C FA synthase gene as one of several rpoS-regulated genes of E. coli and provided for the construction of strains in which proposed cellular functions of CFAs can be properly evaluated.
References
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