UDP-glucose dehydrogenases (EC 126.96.36.199) are responsible for the conversion
of UDP-glucose to UDP-glucuronic acid, a key precursor in the biosynthesis of
glycoconjugates. Herein we report the discovery and characterization of a UDPglucose
dehydrogenase (GbUGD) from Granulibacter bethesdensis, a bacterium
originally isolated from the lymph nodes of patients with chronic granulomatous disease
(CGD). The recombinant form of the protein was expressed in high yield and the
purified enzyme showed highest activity at 37°C/pH 9.0 and was strongly inhibited by Zn2+ ions, sodium dodecyl sulfate
(SDS) and urea. UDP-xylose, an allosteric feedback inhibitor, reduced significantly the activity of the enzyme. High activities
were observed using the co-substrates UDP-glucose and NAD+, whereas no activity could be detected using other
nucleotide sugars or NADP+ as potential alternative substrates. The high activity combined with the simple purification
procedure used make GbUGD a valuable new alternative biocatalyst for the synthesis of UDP-glucuronic acid or the development
of NAD+ regeneration systems.
Keywords: Granulibacter bethesdensis, UDP-glucuronic acid, UDP-glucose dehydrogenase.
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