- Mechanistic insights from substrate preference in unsaturated glucuronyl hydrolase
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Natural and synthetic unsaturated glucuronides were tested as substrates for Clostridium perfringens unsaturated glucuronyl hydrolase to probe its mechanism and to guide inhibitor design. Of the natural substrates, a chondroitin disaccharide substrate with sulfation of the primary alcohol on carbon 6 of its N-acetylgalactosamine moiety was found to have the highest turnover number of any substrate reported for an unsaturated glucuronyl hydrolase, with kcat=112 s-1. Synthetic aryl glycoside substrates with electron-withdrawing aglycone substituents were cleaved more slowly than those with electron-donating substituents. Similarly, an unsaturated glucuronyl fluoride was found to be a particularly poor substrate, with k cat/Km=44 nM-1 s-1 - a very unusual result for a glycoside-cleaving enzyme. These results are consistent with a transition state with positive charge at carbon 5 and the endocyclic oxygen, as anticipated in the hydration mechanism proposed. However, several analogues designed to take advantage of strong enzyme binding to such a transition state showed little to no inhibition. This result suggests that further work is required to understand the true nature of the transition state stabilised by this enzyme. Copyright
- Jongkees, Seino A. K.,Yoo, Hayoung,Withers, Stephen G.
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p. 124 - 134
(2014/01/06)
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- Glucuronidation of alcohols using the bromosugar-iodonium reagent method
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The glycosidation method introduced by Field, employing bromosugars as donors in conjunction with iodine, has been evaluated for glucuronidation. Despite the low donor ability of glucuronates, β-glucuronides were obtained in 70-85% yield from a number of
- Stachulski, Andrew V.
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p. 6611 - 6613
(2007/10/03)
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- Synthesis of self-immolative glucuroenide spacers based on aminomethylcarbamate. Application to 5-fluorouracil prodrugs for antibody-directed enzyme prodrug therapy
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The synthesis of three novel potential glucuronide-based prodrugs for antibody-directed enzyme prodrug therapy (ADEPT) is described. These prodrugs were designed to be activated at the tumour site by -glucuronidase to afford the corrresponding anticancer agent, 5-FU. The structural pattern of these compounds includes a self-immolative spacer between the glucuronyl residue and the N1 of 5-FU. Three types of spacers have been elaborated which, after enzymic hydrolysis, spontaneously decompose to deliver an unstable N1 aminal 5-FU derivative and, from there, the cytotoxic drug. All potential prodrugs were stable and proved to be excellent substrates of E. coll in in vitro experiments.
- Madec-Lougerstay, Rachel,Florent, Jean-Claude,Monneret, Claude
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p. 1369 - 1375
(2007/10/03)
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- Synthesis and biological identification of the acyl glucuronide of the antiinflammatory drug ML-3000
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The synthesis and identification in biological samples of the 1-O-acyl glucuronide 6 of the antiinflammatory drug ML-3000 is described. Starting with D-glucuronic acid γ-lactone, 2,3,4-tris(tert.-butyldimethysilyl) glucuronic acid trichloroethylester 4 wa
- Kirschning, Andreas,Ries, Monika,Domann, Silvie,Martin, Wolfgang,Albrecht, Wolfgang,Arnold, Peter,Laufer, Stefan
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p. 903 - 906
(2007/10/03)
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- Synthesis of glucuronides of α,β-unsaturated carboxylic acids
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A practical synthetic method for glucuronides of α,β-unsaturated carboxylic acids is described.An essential point of this method is the use of groups removable using non-reducing conditions for the protection of the glucuronic acid.
- Tanaka, Masayuki,Okita, Makoto,Yamatsu, Isao
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- A Novel Method for Stereoselective Glucuronidation
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A variety of hydroxylic aglycones can be glucuronidated directly with methyl 2,3,4-tri-O-acetylglucopyranuronate (4a), activated with trimethylsilyl trifluoromethanesulfonate (Me3Si-OTf).This reaction provides mostly β, and sometimes α, glucopyranosiduronic acid derivatives (referred to as glucuronides) rapidly and at low temperatures.The epimeric ratio depends on the relative aglycone nucleophilicity vs. its tendency to form a stabilized carbocation by the formal loss of -OH.Glucuronides of various aromatic and aliphatic aglycones as well as those of a number of cyanohydrins were prepared.The characteristic features of the 1H NMR spectra of α and β derivatives which are presented are useful in the assignment of product stereochemistry and determination of epimeric ratios in those reactions where mixtures are obtained.
- Fischer, Bilha,Nudelman, Abraham,Ruse, Margareta,Herzig, Jacob,Gottlieb, Hugo E.,Keinan, Ehud
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p. 4988 - 4993
(2007/10/02)
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