Structural studies of 4-O-acetyl-alpha-N-acetylneuraminyl-(2 goes to 3)-lactose, the main oligosaccharide in echidna milk.

ABSTRACT

The main oligosaccharide (50%) in the milk of the Australian echidna (Tachyglossus aculeatus) has been identified unequivocally as 4-O-acetyl-alpha-N-acetylneuraminyl-(2 goes to 3)-lactose. The 4-O-acetyl substituent of the sialic acid residue was characterized by g.l.c.-m.s. of the isolated (after mild, acid hydrolysis) and trimethyl-silylated/esterified sialic acid, and by m.s. (after derivatisation) and 500-MHz, 1H-n.m.r. spectroscopy of the intact oligosaccharide. Information about the glycosidic bonds was obtained by methylation analysis and 500-MHz, 1H-n.m.r. spectroscopy. This animals species is the third one known to produce 4-O-acetylated sialic acid.