Structure of the three major sialyl-oligosaccharides excreted in the urine of five patients with three distinct inborn diseases: "I cell disease" and two new types of mucolipidosis.

The urine of five patients with three distinct diseases ("I Cell disease" and two new types of mucolipidosis) contains sialic acid-rich oligosaccharides in a high amount: 50- to 500-fold the normal. The structure of the major components are as follows: alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNac(1 leads to 2)alphaMan(1 leads to 3)betaMan(1 leads to 4)GlcNac,[alphaAcNeu(2 leads to 6)]betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 3)[betaGal(1 leads to 4)betaGlcNac(1 leads to 2)alphaMan(1 leads to 6)]betaMan(1 leads to 4)GlcNAc and alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 3)[alphaAcNeu(2 leads to 6)betaGal(1 leads to 4)betaGlcNAc(1 leads to 2)alphaMan(1 leads to 6)]betaMan(1 leads to 4)GlcNAc. These results suggest that a deficit in alpha-neuraminidase is associated to these three different disorders and that an endo-beta-D-N-acetylglucosaminidase is able to release sialyoligosaccharides by splitting the sialylglycans of glycoproteins.