DEGRADATION OF POLYSACCHARIDES MUCOPOLYSACCHARIDES AND GLYCOPROTEINS BY LYSOSOMAL GLYCOSIDASES

Isolated rat kidney lysosomes are shown to degrade glycogen, starch, hyaluronic acid, ovomucoid, and fetuin. Studies on the release of N-acetylglucosamine from ovomucoid by lysosomes show that proteolytic activity aids in the degradation of the carbohydrate chain by glycosidases. The results indicate that a large portion of the N-acetylhexosamine residues in ovomucoid are terminally located. The sequential action of sialidase, β-galactosidase, and β-N-acetylglucosaminidase releases monosaccharides from fetuin, fetuin glycopeptides, and modified fetuin. The results of these studies, along with those previously published, show that the lysosomes are the sites of intracellular catabolism of glycoproteins. © 1969.