Digestion of asparagine-linked oligosaccharides by endo-beta-N-acetylglucosaminidase in the human skin fibroblasts obtained from fucosidosis patients.

The substrate specificity of human endo-beta-N-acetylglucosaminidase was studied by using the homogenate of cultured skin fibroblasts of fucosidosis patients as an enzyme source. The results indicate that biantennary complex type asparagine-linked sugar chains as well as high mannose type sugar chains are cleaved by the enzyme action. None of the sugar chains with a fucosyl residue on the proximal N-acetylglucosamine of their N,N'-diacetylchitobiose moieties was cleaved. These results proved enzymatically the mechanism of production of oligosaccharides detected in the urine of various exoglycosidase deficiencies.