Glucosidase mannosidase

Inhibition of D-Mannosidases and D-Glucosidases by Swainsonine and Castanospermine, Respectively... 

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. 

Due to the abundance and biological importance of the above mentioned enzymes, the areas of o-glucosidase as well as o-mannosidase inhibitors such as... 

Results are expressed as fig of p-nitrophenol liberated per g of seed from 6 mM p-nitrophenyl a-D-mannoside in 1 hr at 37° and pH 5. Coarsely ground beans. Defatted sweet-almond meal. A commercial /3-D-glucosidase preparation purified from emulsin. a-D-Mannosidase activity is given per g of purified material. 

A somewhat different procedure was needed for purifying the limpet enzyme to the same extent.48 The activity of a-D-mannosidase from this source was rapidly destroyed by pyridine. Selective inactivation of 2-acetamido-2-deoxy-/3-D-glucosidase was, therefore, effected by warming the preparation in 60% ethanol. /3-D-Galacto-sidase was removed in the course of fractionation. 

D-GIucal (l,5-anhydro-2-deoxy-D-ara/nno-hex-l-enitol) has been shown to be a competitive inhibitor of a-D-mannosidase,70 but it has less than one-tenth of the inhibitory power of D-mannono-1,5-lactone. D-Glucal is less specific than D-mannono-1,5-lactone, because it also inhibits a- and /3-D-glucosidases.71... 

The first evidence for the presence of an a-D-mannosyl link in ovalbumin glycopeptides was provided by the action of almond emulsin,101,102 although the absence of /3-D-mannosidase from the enzyme preparation was not confirmed until later.103 The presence of 2-acetamido-2-deoxy-/M>glucosidase in emulsin left doubt as to the terminal position of all of the D-mannose released. 

When the ovalbumin was incubated with purified, jack-bean a-D-mannosidase, at least two molecules of D-mannose per molecule were released, suggesting that these residues are a-D-linked in a terminal position. Two glycopeptides having different contents of hexosamine were subjected to the action of purified 2-acetamido-2-deoxy-/ -D-glucosidase, and, in each case, two hexosamine residues per molecule were either inaccessible, or resistant to attack by the enzyme. 

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