Gangliosides of the starfish Aphelasterias japonica, evidence for a new linkage between two N-glycolylneuraminic acid residues through the hydroxy group of the glycolic acid residue

Abstract

Mono- and disialogangliosides containing glucose, galactose and sialic acids were isolated from the total lipid extract of hepatopancreas of the starfish Aphelasterias japonica. Their structures were elucidated by total and partial acid hydrolysis, trideuteriomethylation analysis, neuraminidase treatment, chromium trioxide oxidation, methanolysis and periodate oxidation. The monosialoganglioside was identified as 8- O-methyl- N-glycolylneuraminosyl- α-(2–3)-galactosyl- β-(1–4)-glucosyl- β-(1-1)-ceramide. The disialoganglioside has th additional N-glycolylneuraminic acid or its 8- O-methyl derivative residue at the subterminal position to which the terminal sialic acid residue is linked through the hydroxy group of the glycolic acid unit The long-chain bases were found to be mixtures of phytosphingosines with both branched and linear chains, and the fatty acids were shown to be mixtures of normal and α-hydroxy fatty acids, the latter amounted to about 90% of the fatty-acid mixtures. The composition of the lipid moieties of the gangliosides was determined by GLC and GLC-MS.