The Structure of a New Sialic Acid-Containing Decasaccharide from the Urine of a Patient with Mucolipidosis

A new sialic acid-containing oligosaccharide has been isolated from urine of a patient with a type of mucolipidosis newly recognized by Orii et al. (1972). This compound was found to be composed of galactose (2 moles), mannose (3 moles), N-acetylglucosamine (3 moles) and sialic acid (2 moles). On the basis of the results of sequential glycosidase digestion, of methylation analysis, and of the Smith degradation, the structure of this oligosaccharide was elucidated as follows: NeuAcalpha2-6Galbeta1-4GlcNAcbeta1-2Manalpha1-3[NeuAcalpha2-6Galbeta1-4GlcNAcbeta1-2Manalpha1-6]Manbeta1-4GlcNAc. The increased excretion of this oligosaccharide may be caused by the impaired metabolism of glycoproteins having N-glycosidic linkage.