Oligosaccharides mannosidase

The protein-bound oligosaccharide is then partially processed by glucosidases and mannosidases if no additional sugars are added, this results in a high-mannose chain. 

Genetic mannosidosis has been described in man, Angus cattle and Murray Gray cattle, and is characterized by a deficiency of a-mannosidase leading to storage of excess mannose-rich oligosaccharides in lysosomes. Pathologically, there is vacuolation of reticuloendothelial cells in the liver and lymph nodes, pancreatic exocrine cells, and neurons. Affected cattle are ataxic, uncoordinated, fail to thrive, and die in the first year of life. 

Singh, S. Scigelova, M. Crout, D. H. G., Glycosidase-catalysed synthesis of oligosaccharides A two-step synthesis of the core trisaccharide of N-hnked glycoproteins using the beta-N-acetylhexosaminidase and the beta-mannosidase from... 

The molecular weight (94,000) was smaller than that of other microbial P-mannosidases such as Aspergillus o/jCTe( 120,000-135,000) and Tremella fuciformis (160,000-200,000). The final product from the oligosaccharides with the enzyme was mainly D-mannose and the enzymatic activity was not inhibited by D-mannose or mannose-derivatives such as D-mannosamine, D-mannonic acid and D-mannitol. 

U. Fuhrmann, E. Bause, G. Legler, and H. Ploegh, Novel mannosidase inhibitor blocking conversion of high mannose to complex oligosaccharides, Nature, 307 (1984) 755-758. 

J. Schweden, G. Legler, and E. Bause, Purification and characterization of a neutral processing mannosidase from calf liver acting on (Man)9(GlcNAc)2 oligosaccharides, Eur. J. Biochem., 157 (1986) 563-570. 

Results of an experiment with an oligosaccharide free from amino acid were less conclusive, but were not incompatible with the structure shown. The oligosaccharide was prepared from a separated glycoprotein fraction having a D-mannose hexosamine ratio of 5 3. a-D-Mannosidase and 2-acetamido-2-deoxy-/3-D-glucosidase were used alternately. Initially, a-D-mannosidase removed about 1.5 D-mannose residues per molecule. Subsequent treatment of the residual oligosaccharide with 2-acetamido-2-deoxy-/3-D-glucosidase released rather less than one proportion of hexosamine residue, and then another 1.5 residues of D-mannose became open to attack by a-D-mannosidase. 

Galactomannans and oligosaccharide fragments are susceptible to hydrolysis by a number of enzymes, including a-D-galactosidase90 (EC 3.2.1.22), /S-D-mannanase, exo-/3-D-mannanase,91 /3-D-mannosidase, and exo-/3-D-mannan mannobiohydrolase (EC 3.2.1.100).92 Early applications of enzymic... 

The differences in the rates of hydrolysis of various linkage types by a particular glycosidase can be used to provide information about this aspect of structure. Jack-bean a-D-mannosidase cleaves a-(l- 2) and a-(l- 6) linkages much faster than a-(l -> 3). Oligosaccharides, obtained by endo-N-acetyl-/J-D-glucosaminidase hydrolysis of ovalbumin, were subjected to acetolysis, which selectively cleaved the a-(l - 6) bonds. A tetrasaccharide isolated after this treatment was then incubated with jack-bean o-d-... 

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