New GM1 Ganglioside Derivatives for Selective Single and Double Labelling of the Natural Glycosphingolipid Skeleton

Selective single and double labelling of the natural ganglioside GM1 enables one to introduce various markers into different parts of the glycosphingolipid molecule without changing the natural skeleton. To that end, N-Fmoc-2-amino-, N-Fmoc-18-amino- and S-(ethoxythiocarbonyl)-18-mercaptostearic acids have been prepared and coupled with the primary amino group in the sphingosine part of lyso-GM1 and deAc-deAcyl-GM1 gangliosides. The products of these coupling reactions - building blocks 16a, 16b, 16c, 26 and 27 - may be used for the synthesis of GM1 derivatives with one or two fluorescent dye moieties or other labels of various polarities. Examples of various labelling strategies, using hydrophilic and lipophilic photostable fluorescent dyes, have been made available. The GM1 derivatives 17a, 22a and 23c labelled with the fluorescent dye ATTO 647N or the doubly labelled derivative 25b can be used as probes in fluorescence correlation spectroscopy (in conventional microscopy or stimulated emission depletion nanoscopy) to study the diffusion of lipid analogues in model or live cell membranes. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)