FURTHER CHARACTERIZATION OF EQUINE BRAIN GANGLIOSIDES - THE PRESENCE OF GM3 HAVING N-GLYCOLYL NEURAMINIC ACID IN THE CENTRAL-NERVOUS-SYSTEM

Equine brain gangliosides were isolated and their structures were char acterized, to examine whether equine brain has N-glycolyl neuraminic a cid in gangliosides, since other mammals predominantly possess N-acety l neuraminic acid in brain gangliosides, and equine erythrocytes and o rgans except the brain have gangliosides exclusively containing N-glyc olyl neuraminic acid, The gangliosides purified from the brain were id entified by proton NMR spectroscopy and mass spectrometry, as well as GLC, resulting in their identification as GM4, GM3, GM2, GM1, GD1a, GD 1b, and GT1b, Of these gangliosides, GM3 possessed N-glycolyl neuramin ic acid as a minor component (18% of the total GM3), whereas other gan gliosides exclusively contained N-acetyl neuraminic acid, The N-glycol yl neuraminic acid residue of the GM3 was confirmed by TLC immunostain ing, The possibility of contamination of the GM3 by erythrocytes was e liminated based on the finding that the lipid compositions were charac teristic of brain gangliosides. The presence, even as a minor componen t, of the N-glycolyl neuraminic acid in equine brain gangliosides is e xceptional among the sialic acid species in mammalian central nervous system.