Catabolism of N-glycosylprotein glycans: evidence for a degradation pathway of sialylglyco-asparagines resulting from the combined action of the lysosomal aspartylglucosaminidase and endo-N-acetyl-beta-D-glucosaminidase. A 400-MHz 1H-NMR study.
A mixture of sialylglycoasparagines and sialylglycopeptides was successively incubated with lysosomal extracts, at two pH values, first at pH 7.5 and then at pH 4. The 1H-NMR analysis of the sialyloligosaccharides released during the enzymatic digestion demonstrates the sequential action of aspartylglucosaminidase and an endo-N-acetyl-beta-D-glucosaminidase which release sialyloligosaccharides identical to the reference sugars isolated from the urine of patients suffering from sialidosis. This process represents a new catabolic pathway for N-glycosyl-proteins which may account for the appearance of the oligosaccharides stored in tissues and urine of patients suffering from lysosomal diseases.
D000118:Acetylglucosaminidase / Q000378:metabolism*; D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D001216:Asparagine / Q000378:metabolism*; D001227:Aspartylglucosylaminase / Q000378:metabolism*; D005260:Female; D006596:Hexosaminidases / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000201:enzymology*; D009682:Magnetic Resonance Spectroscopy; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D019158:N-Acetylneuraminic Acid; D009439:Neuraminidase / Q000172:deficiency; D009844:Oligosaccharides / Q000378:metabolism / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains; D012794:Sialic Acids / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism*
D009844:Oligosaccharides; D012794:Sialic Acids; D012795:Sialoglycoproteins; D001216:Asparagine; D006596:Hexosaminidases; D009439:Neuraminidase; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D000581:Amidohydrolases; D001227:Aspartylglucosylaminase; D019158:N-Acetylneuraminic Acid