Interaction between sulfogalactosylceramide and dimyristoylphosphatidylcholine increases the orientational fluctuation of their lipid hydrocarbon chains.
The objective of this study was to investigate the interaction between sulfogalactosylceramide (SGC) and dimyristoylphosphatidylcholine (DMPC) in a mixed model liposomal system (molar ratio SGC:DMPC, 2:3). Structural and dynamic changes of the liposome components were monitored by Fourier-transform infrared spectroscopy (FTIR). Thermotropic FTIR analysis of the mixed liposomes showed a single gel/liquid crystalline phase transition, centered at approximately 42 degrees C. Spectral changes of the amide and ester C = O bands arising from functional groups at the interfacial region indicated a reduced hydrogen bonding of these groups in the mixed liposomes. Pressure-tuning FTIR of mixed liposomes showed that the methylene chains of SGC and DMPC were more orientationally disordered than those of the individual lipid SGC liposomes or DMPC liposomes. These results suggest that the mixed liposomes (molar ratio SGC:DMPC, 2:3) consisted of a homogeneous mixture of SGC and DMPC molecules in which mutual shielding reduced hydrogen bonding in the interfacial region, with a concurrent increase in the orientational disorder of the hydrocarbon chains of both SGC and DMPC.
Hormone Growth and Development Research Group, Loeb Medical Research Institute, Ottawa, Ont., Canada.
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Attar
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Wong
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Kates
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Carrier
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Jaklis
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Tanphaichitr
D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D005699:Galactosylceramides / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D006860:Hydrogen Bonding; D008081:Liposomes; D017550:Spectroscopy, Fourier Transform Infrared; D013433:Sulfoglycosphingolipids
D005699:Galactosylceramides; D006838:Hydrocarbons; D008081:Liposomes; D013433:Sulfoglycosphingolipids; C084124:I(3)SO3-galactosylceramide; D004134:Dimyristoylphosphatidylcholine