Transferase activity of a beta-glycosidase from Thermus thermophilus: Specificities and limits - Application to the synthesis of beta-[1 -> 3]-disaccharides

The aim of this paper is to test the ability of a P-glycosidase from Thermu s thermophilus to catalyse transglycosylation reactions in the presence of nitrophenyl glycosides as donors and other monosaccharides as accepters. Ou r results show that this enzyme is able to induce such reactions either wit h nitrophenylgalactosides, -glucosides and -fucosides. With the two former donors, the autocondensation of the donor, which thus acts also as an accep tor, is faster than the transglycosylation with other accepters. Furthermor e, as the regioselectivity of the reactions is mainly of the beta-[1-->3] t ype, good yields are obtained for the synthesis of 2-nitrophenyl-beta-D-gal actopyranosyl-[1-->3]-beta-D-galactopyranoside and 2-nitrophenyl-beta-D-glu copyranosyl-[1-->3]-beta-D-glucopyranoside. Conversely, in the presence of p-nitrophenylfucoside, the autocondensation is very limited, and with methy l-alpha-D-galactoside as an acceptor, the regioselectivity is mainly of the beta-[1-->6]-type resulting in the synthesis of methyl-beta-D-fucopyranosy l-[1-->6]-alpha-D-galactopyranoside.