Other UDP-Sugars

Although UDP-Glc has great utility as an intermediate in the regeneration of other sugar nucleotides, it also occasionally functions as the desired glycosyl donor. 

A recycling system for UDP-GlcNAc has been reported for use with pi,6-GlcNAc-transferase (EC 2.4.1.148) [23]. In this study, the authors attempted to use crude yeast cell extracts as the source of UDP-GlcNAc pyrophosphorylase (EC 2.7.7.23). Because of problems with contaminating phosphatases, however, this method was unsuccessful. Stepwise synthesis with whole yeast cells eventually provided the desired trisaccharide product. 

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With bilirubin UDP-glucuronyltransferase from rat liver, Mn-+ was more (HIO), and Ca + less, stimulatory than Mg + (A2, F17, HIO). The behavior was similar when either UDP-glucose or UDP-xylose was used as the glycosyl donor (F3). Enzyme activities were also stimulated by Fe and Co (F3, HIO) Pb + activated glucuronyl transfer but was inhibitory with the other UDP-sugars. The effects of Mg +, Mn +, and Co are in accordance with work of Lucier et al. (L14) on the catalysis of glucuronyl transfer to p-nitrophenol and 1-naphthol by Triton X-100-activated and untreated microsomal material from rat liver. 

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