Synthesis of a fluorescent ganglioside G_M1 derivative and screening of a synthetic peptide library for G_M1 binding sequence motifs

A ganglioside G_M1 probe bearing a dark-red fluorescent dye at the sphingosine moiety of the molecule was prepared by a convenient one-pot synthesis. The labeled G_M1 permitted the detection of the natural ganglioside G_M1 ligand Escherichia coli heat-labile enterotoxin subunit B (EtxB) in picomole quantities on a solid support. When an epitope mapping of several ganglioside binding proteins and protein fragments was performed by screening a cellulose membrane-bound synthetic library of 64 16mer peptides with the new probe, several peptides displaying ganglioside G _M1 affinity could be identified. We consider the labeled glycolipid described herein a versatile tool for manifold biochemical investigations.