Abstract
α-L-Fucosidase partially purified from porcine liver was used for the regioselective synthesis of α-L-fucopyranosyl di- and trisaccharides with p-nitrophenyl a-L-fucopyranoside (Fuc α-pNP) as the donor. In a transglycosylation reaction with p-nitrophenyl β-D-galactopyranoside (Gal β-pNP) as the accep-tor, the enzyme formed mainly Fuc a1→2Gal, β-pNP with its isomers fucosylated at 0-3 or 0-6 of the sugar moiety. The three products were obtained in a ratio of 58: 22 : 20 and in 40.6% overall yield based on the donor added. Replacement of p-nitrophenyl R-D-glucopyranoside by Gal β-pNP resulted in a (1→3) -linked product as the main transfer product along with (1→2) -, (1→4) -, and (1→6) -linked isomers. With p-nitrophenyl β-lactoside acceptor, fucosylation occurred at 0-2', 0-3', and 0-6' of the Gal residue of the acceptor, but the regioselectivity was much lower than that of Gal R-pNP, while the enzyme catalyzed the formation of (1→3) - and (1→4) -linked products with p-nitrophenyl 2-acetamido-2-deoxy-β-D-glucopyranoside acceptor.
