Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract N-acetylhexosaminidase fromNocardia orientalis catalysed the synthesis of lacto-N-triose II glycoside (β-d-GlcNAc-(1-3)-β-d-Gal-(1-4)-β-d-Glc-OMe,3) with its isomers β-d-GlcNAc-(1-6)-β-d-Gal-(1-4)-β-d-Glc-OMe (4) and β-d-Gal-(1-4)-[β-d-GlcNAc-(1-6)]-β-d-Glc-OMe (5) throughN-acetylglucosaminyl transfer fromN,N′-diacetylchitobiose (GlcNAc2) to methyl β-lactoside. The enzyme formed the mixture of trisac-charides3, 4 and5 in 17% overall yield based on GlcNAc2, in a ratio of 20:21:59. Withp-nitrophenyl β-lactoside as an acceptor, the enzyme also producedp-nitrophenyl β-lacto-N-trioside II (β-d-GlcNAc-(1-3)-β-d-Gal-(1-4)-β-d-Glc-OC6H4NO2-p,6) with its isomers β-d-GlcNAc-(1-6)-β-d-Gal-(1-4)-β-d-Glc-OC6H4NO2-p (7) and β-d-Gal-(1-4)-[β-d-GlcNAc-(1-6)]-β-d-Glc-OC6H4NO2-p (8). In this case, when an inclusion complex ofp-nitrophenyl lactoside acceptor with β-cyclodextrin was used, the regioselectivity of glycosidase-catalysed formation of trisaccharide glycoside was substantially changed. It resulted not only in a significant increase of the overall yield of transfer products, but also in the proportion of the desired compound6.
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