![]() ![]() We studied the gastrointestinal and systemic fate of Neu 5 Gc-containing glycoproteins ( Neu 5 Gc-glycoproteins) or free Neu 5 Gc in the Neu 5 Gc-free Cmah(-/-) mouse model. Little is known about how ingested sialic acids in general and Neu 5 Gc in particular are metabolized in the gastrointestinal tract. This accumulation has relevance for diseases associated with such nutrients, via interaction with Neu 5 Gc-specific antibodies. This unexpected expression is hypothesized to result via metabolic incorporation of Neu 5 Gc from mammalian foods. ![]() Although humans cannot produce Neu 5 Gc, it is detected in the epithelial lining of hollow organs, endothelial lining of the vasculature, fetal tissues, and carcinomas. Mammals express two major sialic acids, N-acetylneuraminic acid and N-glycolylneuraminic acid ( Neu 5 Gc). Metabolism of vertebrate amino sugars with N-glycolyl groups: mechanisms underlying gastrointestinal incorporation of the non-human sialic acid xeno-autoantigen N-glycolylneuraminic acid.īanda, Kalyan Gregg, Christopher J Chow, Renee Varki, Nissi M Varki, AjitĪlthough N-acetyl groups are common in nature, N-glycolyl groups are rare. Since Neu 5 Gc is antigenic to man, the observation that this monosaccharide does not or at least only rarely occur in birds and reptiles, may be of nutritional and clinical significance. The few animals where Neu 5 Gc was found, especially in eggs, may have acquired this from the diet or by an alternative pathway. Apparently monotremes (platypus) and sauropsids (birds and reptiles) cannot synthesize Neu 5 Gc. BLAST analysis of the genomes of the platypus, the chicken, and zebra finch against the CMP- N-acetylneuraminic acid hydroxylase did not reveal the existence of a similar protein structure. Among nine reptiles, including one turtle, N-glycolylneuraminic acid was only found in the egg and an adult basilisk, but not in a freshly hatched animal. The nine bird species studied also did not express N-glycolylneuraminic acid with the exception of an egg, but not tissues, from the budgerigar and traces in poultry. In muscle and liver of the platypus only N-acetylneuraminic ( Neu 5Ac) acid was found. They were released from tissues, eggs, or salivary mucin samples by acid hydrolysis, and purified and analyzed by thin-layer chromatography, high-performance liquid chromatography, and mass spectrometry. ![]() The sialic acids of the platypus, birds, and reptiles were investigated with regard to the occurrence of N-glycolylneuraminic ( Neu 5 Gc) acid. Schauer, Roland Srinivasan, G Vinayaga Coddeville, Bernadette Zanetta, Jean-Pierre Guérardel, Yann Low incidence of N-glycolylneuraminic acid in birds and reptiles and its absence in the platypus. ![]()
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