Two novel isoneolacto-undecaglycosylceramides carrying Galα1→3Lewisx on the 6-linked antenna and N-acetylneuraminic acidα2→3 or galactose α1→3 on the 3-linked antenna, expressed in porcine kidney

Three sialosylated and three neutral glycosphingolipids sharing a common iso-neolacto core were isolated from porcine kidney cortex. They were purified by preparative HPTLC, and were characterized by partial exoglycosidase hydrolysis followed by thin layer chromatography and immunostaining with anti-Gal alpha 1-->3Gal, anti-type 2 lactosamine and anti-Lewis(x) antibodies, methylation analysis, MALDI-TOF mass spectrometry and H-1-NMR spectroscopy. Among neutral glycolipids, one was a known structure, (VIVI)-V-3'(3)(alpha Gal)(2)-iso-nLc(8)Cer, and two were novel structures differing by the number of Gal alpha 3Lewis(x) determinants: (VIVI)-V-3'(3)(alpha Gal),V'3 alpha Fuc-iso-nLc(8), and (VIVI)-V-3'(3)(alpha Gal)(2) (VV)-V-3'(3)(alpha Fuc)(2)-iso-nLc(8). The single Gala3Lewis(x) determinant was found on the 6-linked antenna. Among sialosylated glycolipids, two had been previously found in other species and tissues, (VIVI)-V-3'(3)(NeuAc)(2)-iso-nLc(8), and VI(3)NeuAcVI'(3)alpha Gal-iso-nLc(8). A novel structure was discovered presenting a Gal alpha 3Lewis(x) determinant on the 6-linked antenna and a N-acetylneuraminic acid on the 6-linked antenna, VI(3)NeuAcVI'(3 alpha)GalV'(3)alpha Fuc-iso-nLc(8). These results indicate that, in vivo, the porcine kidney alpha 3fucosyltransferase synthesizes the Gal alpha 3Lewis(x) determinant, acting on the 6-linked before the 3-linked Gal alpha 3neolactosamine, and appears unable to synthesize the sialosylated Lewis(x) determinant on neolactoseries glycolipids.