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Glycosidase inhibitors inhibitors of N-linked oligosaccharide processing.The biosynthesis of the various types of N-linked oligosaccharide structures involves two series of reactions 1) the formation of the lipid-linked saccharide precursor, Glc3Man9(GlcNAc)2-pyrophosphoryl-dolichol, by the stepwise addition of GlcNAc, mannose and glucose to dolichyl-P, and 2) the removal of glucose and mannose by membrane-bound glycosidases and the addition of GlcNAc, galactose, sialic acid, and fucose by Golgi-localized glycosyltransferases to produce different complex oligosaccharide structures. For most glycoproteins, the precise role of the carbohydrate is still not known, but specific N-linked oligosaccharide structures are key players in targeting of lysosomal hydrolases to the lysosomes, in the clearance of asialoglycoproteins from the serum, and in some cases of cellcell adhesion. Furthermore, many glycoproteins have more than one N-linked oligosaccharide, and these oligosaccharides on the same protein frequently have different structures. Thus, one oligosaccharide may be of the high-mannose type whereas another may be a complex chain. One approach to determining the role of specific structures in glycoprotein function is to use inhibitors that block the modification reactions at different steps, causing the cell to produce glycoproteins with altered carbohydrate structures.

The function of these glycoproteins can then be assessed. A number of alkaloid-like compounds have been identified that are specific inhibitors of the glucosidases and mannosidases involved in glycoprotein processing. These compounds cause the formation of glycoproteins with glucose-containing high mannose structures, or various high-mannose or hybrid chains, depending on the site of inhibition. Purchase have also been useful for studying the processing pathway and for comparing processing enzymes from different organisms.Interactions of cartilage proteoglycans with hyaluronate. Inhibition of the interaction by modified oligomers of hyaluronate.Oligomers of hyaluronic acid were prepared by digestion of hyaluronic acid from rooster combs with testicular hyaluronidase (hyaluronate 4-glycanohydrolase, EC 35), leech head hyaluronidase (hyaluronate 3-glycanohydrolase, EC 36), and with fungal hyaluronidase (hyaluronate lyase from Streptomyces hyalurolyticus).

The oligomers were fractionated by gel permeation, using Sephadex G-. Oligomers isolated after incubation of the hyaluronic acid with the testicular hyaluronidase were further modified. To prepare oligomers with N-acetylglucosamine at both ends, terminal nonreducing glucuronic acid residues were removed with beta-glucuronidase. Reducing terminal N-acetylglucosamine residues were removed by reaction under mildly alkaline conditions. The reducing terminal N-acetylglucosamine residues were also reduced with sodium borohydride to form N-acetylglucosaminitol. The potentials of the various oligosaccharides to bind to the proteoglycan from bovine nasal septum cartilage were estimated by determining their effectiveness as inhibitors of the proteoglycan-hyaluronate interaction. human milk oligosaccharides shows that, to bind maximally to the proteoglycan, the hyaluronate oligosaccharide must be at least sugar residues in length and be terminated at the nonreducing and reducing ends with a glucuronate residue and an N-acetylglucosamine residue, respectively.

Sugar residues extended beyond this basic decasaccharide, do not interact with the hyaluronate binding site on the proteoglycan.Cellulolytic activity of aerobic soil actinomycetes.The cellulolytic activity of several aerobic soil actinomycetes against insoluble cellulose and soluble cellulose derivatives were isolated after enrichment growth and purification on the same synthetic medium. The actinomycete strains were able to degrade insoluble cellulose, with the production of cellobiose and various oligosaccharide intermediates as degradation products, indicating the random attack of the cellulose chain. The actinomycete strains showed also a great activity against soluble cellulose increase in reducing compounds. The degree of substitution of CMC solutions had an effect on the degradation by the actinomycetes. The degree of polymerization did not affect the rate of hydrolysis, however.