Enzymatic Glycosylations with Non-Natural Donors and Acceptors

27 Enzymatic Glycosylations with Non-Natural Donors and Acceptors 

Xiangping Qian, Keiko Sujino, and Monica M. Palcic 

Interestingly, UDP-5 -thio-Gal, with the ring oxygen of Gal replaced by a sulfur atom, was active as a donor substrate for pi,4-GalT [37]. UDP-5 -thio-GalNAc was also found to be a substrate in the presence of lactalbumin [38]. 

Analogs with the 3-OH group deoxygenated [44, 45], alkylated with a methyl or allyl group, or oxidized to the ketone are active as acceptors although the relative rates of transfer are much lower than to iV-acetylglucosamine [45], 

Unlike pi,4-GalT, al,3-galactosyltransferase has a rather restricted specificity for the nucleotide donor substrate as revealed by studies with recombinant murine al,3-GalT [63]. Although UDP-Glc, UDP-GalNAc, UDP-GlcNAc, and UDP-glucuronic acid are not substrates for the enzyme [63], UDP-2-deoxy-Gal is a better substrate than UDP-Gal. The relative rates of transfer of 3-deoxy, 4-deoxy, or 6-deoxy donors are 0.2, 0.6 and 2% that of UDP-Gal [64]. 

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Palcic MM, Sujino K, Qian X. Enzymatic glycosylations with non-natural donors and acceptors. Carbohydr Chem Biol 2000 2 685-703. 

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