FTIR spectroscopic analysis of the amide and acid bands of ganglioside GM1, in pure form and in mixtures with DMPC.
The amide I bands of sphingolipids show complicated patterns due to intra- and intermolecular interactions via hydrogen bonds. In order to assign the amide I absorption bands of the ganglioside GM1 to the different amide groups in the headgroup and back bone, the compounds N-acetylgalactosamine, N-acetylneuraminic acid, glucocerebroside and ceramide III were examined as reference systems. The frequencies of the COOH and COO- bands of the sialic acid residue of GM1 were determined by pH-titration and were found to absorb at 1729 cm-1 and 1605 cm-1, respectively. In D2O the three amide groups of GM1 give one broad absorption band at 1627 cm-1, whereas in the glucocerebroside intra- and intermolecular interactions of the amide group give rise to three distinct amide I bands. For a solid sample of GM1 in KBr also one broad band was observed in the amide I region. We also studied the influence of the ganglioside GM1 on model membranes of DMPC as host lipid. The change of the CH2 stretching vibrational absorption bands as a function of temperature reveal that addition of GM1 to DMPC leads to increased phase transition temperatures Tm with increasing ganglioside content. No Ca2+ binding to the COO- group of GM1 was observed.
Mueller
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Fachbereich Chemie, University of Kaiserslautern, Germany.
Blume
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A
D000116:Acetylgalactosamine / Q000737:chemistry; D000577:Amides / Q000032:analysis*; D000818:Animals; D002118:Calcium; D002240:Carbohydrate Sequence; D002417:Cattle; D002518:Ceramides / Q000737:chemistry; D004134:Dimyristoylphosphatidylcholine; D005227:Fatty Acids / Q000032:analysis* / Q000737:chemistry; D005677:G(M1) Ganglioside / Q000737:chemistry*; D005963:Glucosylceramides / Q000737:chemistry; D007477:Ions; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019158:N-Acetylneuraminic Acid; D012794:Sialic Acids / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods; D013696:Temperature
D000577:Amides; D002518:Ceramides; D005227:Fatty Acids; D005963:Glucosylceramides; D007477:Ions; D012794:Sialic Acids; D005677:G(M1) Ganglioside; D019158:N-Acetylneuraminic Acid; D000116:Acetylgalactosamine; D002118:Calcium; D004134:Dimyristoylphosphatidylcholine