Detection of ganglioside clustering in DOPC bilayers by 1H-NMR spectroscopy

1H-NMR spectroscopy has been used to investigate the formation of GM1 clusters in DOPC liposome bilayer. The 1H-DOPC NMR spectra show that the presence of GM1 modifies some resonance lines. These modifications are imputable to the interaction of DOPC with GM1. Above a certain GM1 concentration the trend of such distortions suggests the formation of GM1 aggregates. This work provides a new and simple NMR proof of the GM1 clustering in DOPC liposomes and therefore on model cell membranes; it allows to estimate the mean size of GM1 aggregates and the GM1 concentration at which clustering starts. In addition, the behaviour of the 1H-NMR line-width shows that the presence of GM1 modifies the bilayer arrangement making it more mobile, especially at GM1-clustering concentration.