Effect of modification of carbohydrate component on properties of glucoamylase

In this study, we investigated enzymatic deglycosylation of glucoamylase from Aspergillus awamori X 100/D27, a glycoprotein which has two N-linked and about forty short mannose-bearing O-linked sugars per molecule. O-Linked sugars were modified by treatment with alpha-mannosidase and N-linked sugars were removed using endo-beta-N-acetylglucosaminidase F. Analysis of conformational changes following deglycosylation suggests that O-linked sugars essentially contribute to the stabilization of glucoamylase domains. Modification of the carbohydrate component by adding 1-deoxymannojirimycin to the culture medium induced inhibition of alpha-mannosidases involved in the processing, leading to a more complete glycosylation and, consequently, to a higher stability of the enzyme.