Characterization of binding of Gal beta 4GlcNAc-specific lectins from Erythrina cristagalli and Erythrina corallodendron to glycosphinogolipids. Detection, isolation, and characterization of a novel glycosphinglipid of bovine buttermilk.

The lectins from seeds of Erythrina cristagalli and Erythrina corallodendron were characterized for binding to glycolipids, using a chromatogram binding assay, a microtiter well assay, and glycolipids coated on erythrocytes. Both lectins bound to glycolipids having a terminal Gal beta 4GlcNAc sequence and also, with similar affinity, to glycolipids with terminal Fuc alpha 2Gal beta 4GlcNAc (blood group H determinant on a type 2 chain). All other substitutions of Gal beta 4GlcNAc tested abolished the binding. A binding epitope for the Erythrina lectins was considered by comparison of minimum energy conformations of binding and nonbinding glycolipids. A non-acid glycolipid, with lectin binding activity, was found in bovine buttermilk. By mass spectrometry and proton NMR spectroscopy it was shown to be a branched hexaglycosylceramide with the structure Gal beta 4Glc-NAc beta 6(Gal beta 4GlcNAc beta 3)Gal beta 4Glc beta Cer. This glycosphingolipid has not been reported before.