2616-64-0Relevant articles and documents
Identification of novel inhibitors of UDP-Glc 4′-epimerase, a validated drug target for african sleeping sickness
Urbaniak, Michael D.,Tabudravu, Jioji N.,Msaki, Aichi,Matera, Kathy Mansfield,Brenk, Ruth,Jaspars, Marcel,Ferguson, Michael A.J.
, p. 5744 - 5747 (2006)
Novel inhibitors of Trypanosoma brucei and mammalian UDP-Glc 4′-epimerase were identified by screening a small library of natural products and commercially available drug-like molecules. The inhibitors possess low micromolar potency against the T. brucei and human enzymes in vitro, display a degree of selectivity between the two enzymes, and are cytotoxic to cultured T. brucei and mammalian cells.
Enzymatic Synthesis of Uridine 5'-Diphosphoglucuronic Acid on a Gram Scale
Toone, Eric J.,Simon, Ethan S.,Whitesides, George M.
, p. 5603 - 5606 (1991)
A pratical route to uridine 5'-diphosphoglucuronic acid (UDP-GlcUA) from uridine 5'-diphosphoglucose (UDP-Glc) on a 1-g scale has been developed using uridine 5'-diphosphoglucose dehydrogenase (UDP-Glc DH, EC 1.1.1.22) from bovine liver.Crude UDP-Glc dehydrogenase was isolated fron beef liver (450 units from 2.4 kg of frozen liver).Commercially available UDP-Glc dehydrogenase as well as a preparation fron calf liver acetone powder were also evaluated as catalysts for large-scale production of UDP-GlcUA: both preparations exhibited too little activity to be synthetically useful.A platinum-catalyzed oxygen oxidation of UDP-Glc was also examined as a possible route to UDP-GlcUA: enzymatic oxidation was superior.These results establish a route to another of the important activated monosaccharides required for cell-free enzymatic syntheses of mammalian oligo- and polysaccharides.
Catalytic mechanism of human UDP-glucose 6-dehydrogenase: In situ proton NMR studies reveal that the C-5 hydrogen of UDP-glucose is not exchanged with bulk water during the enzymatic reaction
Eixelsberger, Thomas,Brecker, Lothar,Nidetzky, Bernd
, p. 209 - 214 (2012)
Human UDP-glucose 6-dehydrogenase (hUGDH) catalyzes the biosynthetic oxidation of UDP-glucose into UDP-glucuronic acid. The catalytic reaction proceeds in two NAD+-dependent steps via covalent thiohemiacetal and thioester enzyme intermediates. Formation of the thiohemiacetal adduct occurs through attack of Cys276 on C-6 of the UDP-gluco-hexodialdose produced in the first oxidation step. Because previous studies of the related enzyme from bovine liver had suggested loss of the C-5 hydrogen from UDP-gluco-hexodialdose due to keto-enol tautomerism, we examined incorporation of solvent deuterium into product(s) of UDP-glucose oxidation by hUGDH. We used wild-type enzyme and a slow-reacting Glu161→Gln mutant that accumulates the thioester adduct at steady state. In situ proton NMR measurements showed that UDP-glucuronic acid was the sole detectable product of both enzymatic transformations. The product contained no deuterium at C-5 within the detection limit (≤2%). The results are consistent with the proposed mechanistic idea for hUGDH that incipient UDP-gluco-hexodialdose is immediately trapped by thiohemiacetal adduct formation.
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Mills et al.
, p. 103,105 (1958)
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Uridine diphosphate beta-glucuronic acid. A new substrate for beta-glucuronidase.
Das,Wentworth,Ide,Sie,Fishman
, p. 375 - 377 (1970)
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Mechanistic characterization of UDP-glucuronic acid 4-epimerase
Borg, Annika J. E.,Dennig, Alexander,Weber, Hansj?rg,Nidetzky, Bernd
, p. 1163 - 1178 (2020/08/07)
UDP-glucuronic acid (UDP-GlcA) is a central precursor in sugar nucleotide biosynthesis and common substrate for C4-epimerases and decarboxylases releasing UDP-galacturonic acid (UDP-GalA) and UDP-pentose products, respectively. Despite the different reactions catalyzed, the enzymes are believed to share mechanistic analogy rooted in their joint membership to the short-chain dehydrogenase/reductase (SDR) protein superfamily: Oxidation at the substrate C4 by enzyme-bound NAD+ initiates the catalytic pathway. Here, we present mechanistic characterization of the C4-epimerization of UDP-GlcA, which in comparison with the corresponding decarboxylation has been largely unexplored. The UDP-GlcA 4-epimerase from Bacillus cereus functions as a homodimer and contains one NAD+/subunit (kcat?=?0.25?±?0.01?s?1). The epimerization of UDP-GlcA proceeds via hydride transfer from and to the substrate’s C4 while retaining the enzyme-bound cofactor in its oxidized form (≥?97%) at steady state and without trace of decarboxylation. The kcat for UDP-GlcA conversion shows a kinetic isotope effect of 2.0 (±0.1) derived from substrate deuteration at C4. The proposed enzymatic mechanism involves a transient UDP-4-keto-hexose-uronic acid intermediate whose formation is rate-limiting overall, and is governed by a conformational step before hydride abstraction from UDP-GlcA. Precise positioning of the substrate in a kinetically slow binding step may be important for the epimerase to establish stereo-electronic constraints in which decarboxylation of the labile β-keto acid species is prevented effectively. Mutagenesis and pH studies implicate the conserved Tyr149 as the catalytic base for substrate oxidation and show its involvement in the substrate positioning step. Collectively, this study suggests that based on overall mechanistic analogy, stereo-electronic control may be a distinguishing feature of catalysis by SDR-type epimerases and decarboxylases active on UDP-GlcA.
Isotope Probing of the UDP-Apiose/UDP-Xylose Synthase Reaction: Evidence of a Mechanism via a Coupled Oxidation and Aldol Cleavage
Eixelsberger, Thomas,Horvat, Doroteja,Gutmann, Alexander,Weber, Hansj?rg,Nidetzky, Bernd
supporting information, p. 2503 - 2507 (2017/02/23)
The C-branched sugar d-apiose (Api) is essential for plant cell-wall development. An enzyme-catalyzed decarboxylation/pyranoside ring-contraction reaction leads from UDP-α-d-glucuronic acid (UDP-GlcA) to the Api precursor UDP-α-d-apiose (UDP-Api). We examined the mechanism of UDP-Api/UDP-α-d-xylose synthase (UAXS) with site-selectively2H-labeled and deoxygenated substrates. The analogue UDP-2-deoxy-GlcA, which prevents C-2/C-3 aldol cleavage as the plausible initiating step of pyranoside-to-furanoside conversion, did not give the corresponding Api product. Kinetic isotope effects (KIEs) support an UAXS mechanism in which substrate oxidation by enzyme-NAD+and retro-aldol sugar ring-opening occur coupled in a single rate-limiting step leading to decarboxylation. Rearrangement and ring-contracting aldol addition in an open-chain intermediate then give the UDP-Api aldehyde, which is intercepted via reduction by enzyme-NADH.