Endo-a-mannosidase

Izumi, M, Suhara, Y, Ichikawa, Y, Design and synthesis of potential inhibitors of Golgi endo-a-mannosidase 5-Thio-D-glucopyranosyl-a(l-3)-l-deoxymannojirimycin and methyl 5-thio-D-glu-copyranosyl-a(l-3)5-thio-a-D-mannopyranoside, J. Org. Chem., 63, 4811-4816, 1998. 

Spiro, M., V. Bhoyroo, and R. Spiro, Molecular cloning and expression of rat liver endo-a-mannosidase, an N-linked oligosaccharide processing enzyme, J. Biol Chem., 1997, 272, 29356-29363. 

For degradation of the carbohydrate moiety of 50 mg ARS2 sample, 10 or 25 U exo-P-galactosidase were added and the mixture was incubated at 37°C for 18 hr 10 ml of 100 mM acetate buffer (pH 4.2) containing 25 U endo-P-1,4-galactanase or 1 mg crude endo-P-1,6-galactanase [43] were added and the mixture was incubated at 45°C for 48 hr. Fifty unit exo-a-mannosidase or 0.5 U endo-P-galactosidase in 50 mM potassium phosphate buffer (pH 6.0) at 37 °C for 18 h was also used. 

Lubas, W. A., and Spiro, R. G. (1988). Evaluation of the role of rat liver golgi endo-a-D-mannosidase in processing N-linked oligosaccharides. J. Biol. Chem., 263, 3990-3998. 

EC 3.2.1.101 mannan endo-1,6-a-mannosidase Random hydrolysis of 1,6-a-D-mannosidic linkages in unbranched 1,6-mannans... 

Ding, Y, Hindsgaul, O, Syntheses of l-deoxy-3-5 -(l-thio-a-D-glucopyranosyl)-mannojirimycin and l-deoxy-3-0-(5-thio-a-D-glucopyranosyl)-mannojirimycin as potential inhibitors of endo-a-D-mannosidase, Bioorg. Med Chem. Lett., 8, 1215-1220, 1998. 

For example, the 3-0-(5-thio-a-D-glucopyranosyl) derivative of 1-deoxymannojirimycin (60), a powerful D-mannosidase inhibitor, was synthesized as a potential inhibitor of endo-a-D-mannosidase of glycoprotein trimming [150]. 

Lubas, W., and R. Spiro, Golgi endo-a-D-mannosidase from rat liver, a novel N-linked carbohydrate unit processing enzyme, J. Biol. Chem., 1987, 262, 3775- 3781. 

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-... 

According to Reese and Shibata,221 the biodegradative hydrolysis of galactomannan requires at least three different enzymes, namely, a-D-galactosidase, endo-/3-D-mannanase, and j3-D-mannosidase. In addition to these enzymes, there is also a report222 of a phosphorylase, identified as oligo-j8-D-mannosyl-(l— 4)-phosphorylase, which may take part in the degradation. These enzymes will now be discussed in detail. 

Proteins of a crude enzyme preparation obtained from the cultivation medium of the basidiomycete Phellinus abietis were separated by gel filtration and ion-exchange chromatography. The preparation contained a minimum of three enzymes capable of splitting a-D-mannosidic bonds a-D-mannosidase, exo-D-mannanase, and endo-D-mannanase, which were separated. Some properties of the D-mannanase complex of the crude enzyme preparation were examined. The D-mannanase complex exhibited two pH optima, its temperature optimum being at 45 C. 

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