Regioselective synthesis of α-L-fucosyl-containing benzyl disaccharides by use of α-L-fucosidases ofAspergillus niger

Production and characterization of Aspergillus niger GH29 family α-fucosidase and production of a novel non-reducing 1-fucosyllactose

Fucosylated oligosaccharides are interesting molecules due to their bioactive properties. In particular, their application as active ingredient in milk powders is attractive for dairy industries. The objective of this study was to characterize the glycosyl hydrolase family 29 α-fucosidase produced by Aspergillus niger and test its ability to transfucosylate lactose with a view towards potential industrial applications such as the valorization of the lactose side stream produced by dairy industry. In order to reduce costs and toxicity the use of free fucose instead of environmentally questionable fucose derivatives was studied. In contrast to earlier studies, a recombinantly produced A. niger α-fucosidase was utilized. Using pNP-fucose as substrate, the optimal pH for hydrolytic activity was determined to be 3.8. The optimal temperature for a 30-min reaction was 60 °C, and considering temperature stability, the optimal temperature for a 24-h reaction was defined as 45 °C For the same hydrolysis reaction, the kinetic values were calculated to be 0.385 mM for the K_M and 2.8 mmol/(mg*h) for the V_max. Transfucosylation of lactose occurred at high substrate concentrations when reaction time was elongated to several days. The structure of the product trisaccharide was defined as 1-fucosyllactose, where fucose is α-linked to the anomeric carbon of the β-glucose moiety of lactose. Furthermore, the enzyme was able to hydrolyze its own transfucosylation product and 2′-fucosyllactose but only poorly 3-fucosyllactose. As a conclusion, α-fucosidase from A. niger can transfucosylate lactose using free fucose as substrate producing a novel non-reducing 1-fucosyllactose.

An alpha-L-fucosidase from Penicillium multicolor as a candidate enzyme for the synthesis of alpha (1-->3)-linked fucosyl oligosaccharides by transglycosylation

A new alpha-L-fucosidase was partially purified from the culture broth of Penicillium multicolor, which was available commercially as a freeze dried powder by the name of Lactase-P. This enzyme catalysed the transglycosylation of fucose residue of p-nitrophenyl-alpha-L-fucopyranoside to give alpha-L-Fuc-(1-->3)-D-Glc or alpha-L-Fuc-(1-->3)-D-GlcNAc regioselectively. This enzyme was more stable in the organic co-solvents than the alpha-fucosidase from Aspergillus niger, which was also proposed previously by us as an enzyme to produce fucosyl oligosaccharides.