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Abstract
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Fluorinated
carbohydrates have found many applications in the glycosciences.
Typically, these contain fluorination at a single position. There
are not many applications involving polyfluorinated carbohydrates,
here defined as monosaccharides in which more than one carbon has
at least one fluorine substituent directly attached to it, with the
notable exception of their use as mechanism-based inhibitors. The
increasing attention to carbohydrate physical properties, especially
around lipophilicity, has resulted in a surge of interest for this
class of compounds. This review covers the considerable body of work
toward the synthesis of polyfluorinated hexoses, pentoses, ketosugars,
and aminosugars including sialic acids and nucleosides. An overview
of the current state of the art of their glycosidation is also provided.
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Affiliation(s)
- Kler Huonnic
- School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K
| | - Bruno Linclau
- School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K.,Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre, Krijgslaan 281-S4, Ghent, 9000, Belgium
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2
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Council CE, Kilpin KJ, Gusthart JS, Allman SA, Linclau B, Lee SS. Enzymatic glycosylation involving fluorinated carbohydrates. Org Biomol Chem 2021; 18:3423-3451. [PMID: 32319497 DOI: 10.1039/d0ob00436g] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Fluorinated carbohydrates, where one (or more) fluorine atom(s) have been introduced into a carbohydrate structure, typically through deoxyfluorination chemistry, have a wide range of applications in the glycosciences. Fluorinated derivatives of galactose, glucose, N-acetylgalactosamine, N-acetylglucosamine, talose, fucose and sialic acid have been employed as either donor or acceptor substrates in glycosylation reactions. Fluorinated donors can be synthesised by synthetic methods or produced enzymatically from chemically fluorinated sugars. The latter process is mediated by enzymes such as kinases, phosphorylases and nucleotidyltransferases. Fluorinated donors produced by either method can subsequently be used in glycosylation reactions mediated by glycosyltransferases, or phosphorylases yielding fluorinated oligosaccharide or glycoconjugate products. Fluorinated acceptor substrates are typically synthesised chemically. Glycosyltransferases are most commonly used in conjunction with natural donors to further elaborate fluorinated acceptor substrates. Glycoside hydrolases are used with either fluorinated donors or acceptors. The activity of enzymes towards fluorinated sugars is often lower than towards the natural sugar substrates irrespective of donor or acceptor. This may be in part attributed to elimination of the contribution of the hydroxyl group to the binding of the substrate to enzymes. However, in many cases, enzymes still maintain a significant activity, and reactions may be optimised where necessary, enabling enzymes to be used more successfully in the production of fluorinated carbohydrates. This review describes the current state of the art regarding chemoenzymatic production of fluorinated carbohydrates, focusing specifically on examples of the enzymatic production of activated fluorinated donors and enzymatic glycosylation involving fluorinated sugars as either glycosyl donors or acceptors.
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Affiliation(s)
- Claire E Council
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
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3
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Li J, Hsu HC, Mountz JD, Allen JG. Unmasking Fucosylation: from Cell Adhesion to Immune System Regulation and Diseases. Cell Chem Biol 2018. [DOI: 10.1016/j.chembiol.2018.02.005] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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4
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Wetterhorn KM, Newmister SA, Caniza RK, Busman M, McCormick SP, Berthiller F, Adam G, Rayment I. Crystal Structure of Os79 (Os04g0206600) from Oryza sativa: A UDP-glucosyltransferase Involved in the Detoxification of Deoxynivalenol. Biochemistry 2016; 55:6175-6186. [DOI: 10.1021/acs.biochem.6b00709] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karl M. Wetterhorn
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Sean A. Newmister
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Rachell K. Caniza
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Mark Busman
- Mycotoxin
Prevention and Applied Microbiology Research Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois 61604, United States
| | - Susan P. McCormick
- Mycotoxin
Prevention and Applied Microbiology Research Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois 61604, United States
| | - Franz Berthiller
- Christian
Doppler Laboratory for Mycotoxin Metabolism, Center for Analytical
Chemistry, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad-Lorenz-Strasse
20, 3430 Tulln, Austria
| | - Gerhard Adam
- Department
of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria
| | - Ivan Rayment
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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5
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Li L, Liu Y, Li T, Wang W, Yu Z, Ma C, Qu J, Zhao W, Chen X, Wang PG. Efficient chemoenzymatic synthesis of novel galacto-N-biose derivatives and their sialylated forms. Chem Commun (Camb) 2015; 51:10310-3. [PMID: 26023910 PMCID: PMC4498953 DOI: 10.1039/c5cc03746h] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Galacto-N-biose (GNB) derivatives were efficiently synthesized from galactose derivatives via a one-pot two-enzyme system containing two promiscuous enzymes from Bifidobacterium infantis: a galactokinase (BiGalK) and a d-galactosyl-β1-3-N-acetyl-d-hexosamine phosphorylase (BiGalHexNAcP). Mono-sialyl and di-sialyl galacto-N-biose derivatives were then prepared using a one-pot two-enzyme system containing a CMP-sialic acid synthetase and an α2-3-sialyltransferase or an α2-6-sialyltransferase.
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Affiliation(s)
- Lei Li
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China
| | - Yonghui Liu
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China
| | - Tiehai Li
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - Wenjun Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China
| | - Zaikuan Yu
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - Cheng Ma
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - Jingyao Qu
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
| | - Wei Zhao
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, PR China
| | - Xi Chen
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Peng G Wang
- Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
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Brühlmann D, Jordan M, Hemberger J, Sauer M, Stettler M, Broly H. Tailoring recombinant protein quality by rational media design. Biotechnol Prog 2015; 31:615-29. [DOI: 10.1002/btpr.2089] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/04/2015] [Indexed: 02/07/2023]
Affiliation(s)
- David Brühlmann
- Merck Serono SA, Corsier-sur-Vevey, Biotech Process Sciences, Zone Industrielle B; CH-1809 Fenil-sur-Corsier Switzerland
- Dept. of Biotechnology and Biophysics; Julius-Maximilians-Universität Würzburg, Biozentrum; Am Hubland DE-97074 Würzburg Germany
| | - Martin Jordan
- Merck Serono SA, Corsier-sur-Vevey, Biotech Process Sciences, Zone Industrielle B; CH-1809 Fenil-sur-Corsier Switzerland
| | - Jürgen Hemberger
- Inst. for Biochemical Engineering and Analytics; University of Applied Sciences Giessen; Wiesenstrasse 14, DE-35390 Giessen Germany
| | - Markus Sauer
- Dept. of Biotechnology and Biophysics; Julius-Maximilians-Universität Würzburg, Biozentrum; Am Hubland DE-97074 Würzburg Germany
| | - Matthieu Stettler
- Merck Serono SA, Corsier-sur-Vevey, Biotech Process Sciences, Zone Industrielle B; CH-1809 Fenil-sur-Corsier Switzerland
| | - Hervé Broly
- Merck Serono SA, Corsier-sur-Vevey, Biotech Process Sciences, Zone Industrielle B; CH-1809 Fenil-sur-Corsier Switzerland
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Wong CH. Design and Synthesis of Carbohydrate Mimetics: A New Strategy for Tackling the Problem of Carbohydrate-Mediated Biological Recognition. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.199900043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Rillahan CD, Antonopoulos A, Lefort CT, Sonon R, Azadi P, Ley K, Dell A, Haslam SM, Paulson JC. Global metabolic inhibitors of sialyl- and fucosyltransferases remodel the glycome. Nat Chem Biol 2012; 8:661-8. [PMID: 22683610 PMCID: PMC3427410 DOI: 10.1038/nchembio.999] [Citation(s) in RCA: 315] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 05/05/2012] [Indexed: 12/23/2022]
Abstract
Despite the fundamental roles of sialyl- and fucosyltransferases in mammalian physiology, there are few pharmacological tools to manipulate their function in a cellular setting. Although fluorinated analogs of the donor substrates are well-established transition state inhibitors of these enzymes, they are not membrane permeable. By exploiting promiscuous monosaccharide salvage pathways, we show that fluorinated analogs of sialic acid and fucose can be taken up and metabolized to the desired donor substrate-based inhibitors inside the cell. Because of the existence of metabolic feedback loops, they also act to prevent the de novo synthesis of the natural substrates, resulting in a global, family-wide shutdown of sialyl- and/or fucosyltransferases and remodeling of cell-surface glycans. As an example of the functional consequences, the inhibitors substantially reduce expression of the sialylated and fucosylated ligand sialyl Lewis X on myeloid cells, resulting in loss of selectin binding and impaired leukocyte rolling.
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Affiliation(s)
- Cory D. Rillahan
- Department of Chemical Physiology The Scripps Research Institute La Jolla, CA 92037 (USA)
| | - Aristotelis Antonopoulos
- Division of Molecular Biosciences Faculty of Natural Sciences mperial College London, London SW7 2AZ (UK)
| | - Craig T. Lefort
- La Jolla Institute for Allergy and Immunology Division of Inflammation Biology La Jolla, CA 92037 (USA)
| | - Roberto Sonon
- Complex Carbohydrate Research Center The University of Georgia Athens, GA 30602 (USA)
| | - Parastoo Azadi
- Complex Carbohydrate Research Center The University of Georgia Athens, GA 30602 (USA)
| | - Klaus Ley
- La Jolla Institute for Allergy and Immunology Division of Inflammation Biology La Jolla, CA 92037 (USA)
| | - Anne Dell
- Division of Molecular Biosciences Faculty of Natural Sciences mperial College London, London SW7 2AZ (UK)
| | - Stuart M. Haslam
- Division of Molecular Biosciences Faculty of Natural Sciences mperial College London, London SW7 2AZ (UK)
| | - James C. Paulson
- Department of Chemical Physiology The Scripps Research Institute La Jolla, CA 92037 (USA)
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Durantie E, Bucher C, Gilmour R. Fluorine-directed β-galactosylation: chemical glycosylation development by molecular editing. Chemistry 2012; 18:8208-15. [PMID: 22592962 DOI: 10.1002/chem.201200468] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Indexed: 11/10/2022]
Abstract
Validation of the 2-fluoro substituent as an inert steering group to control chemical glycosylation is presented. A molecular editing study has revealed that the exceptional levels of diastereocontrol in glycosylation processes by using 2-fluoro-3,4,6-tri-O-benzyl glucopyranosyl trichloroacetimidate (TCA) scaffolds are a consequence of the 2R,3S,4S stereotriad. This study has also revealed that epimerization at C4, results in a substantial enhancement in β-selectivity (up to β/α 300:1).
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Affiliation(s)
- Estelle Durantie
- Laboratory for Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland
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van der Peet P, Ralton JE, McConville MJ, Williams SJ. Discovery of inhibitors of Leishmania β-1,2-mannosyltransferases using a click-chemistry-derived guanosine monophosphate library. PLoS One 2012; 7:e32642. [PMID: 22393429 PMCID: PMC3290622 DOI: 10.1371/journal.pone.0032642] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 01/28/2012] [Indexed: 12/20/2022] Open
Abstract
Leishmania spp. are a medically important group of protozoan parasites that synthesize a novel intracellular carbohydrate reserve polymer termed mannogen. Mannogen is a soluble homopolymer of β-1,2-linked mannose residues that accumulates in the major pathogenic stages in the sandfly vector and mammalian host. While several steps in mannogen biosynthesis have been defined, none of the enzymes have been isolated or characterized. We report the development of a simple assay for the GDP-mannose–dependent β-1,2-mannosyltransferases involved in mannogen synthesis. This assay utilizes octyl α-d-mannopyranoside to prime the formation of short mannogen oligomers up to 5 mannose residues. This assay was used to screen a focussed library of 44 GMP-triazole adducts for inhibitors. Several compounds provided effective inhibition of mannogen β-1,2-mannosyltransferases in a cell-free membrane preparation. This assay and inhibitor compounds will be useful for dissecting the role of different mannosyltransferases in regulating de novo biosynthesis and elongation reactions in mannogen metabolism.
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Affiliation(s)
- Phillip van der Peet
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Julie E. Ralton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- * E-mail: (MJM); (SJW)
| | - Spencer J. Williams
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- * E-mail: (MJM); (SJW)
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11
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Design and synthesis of novel cell wall inhibitors of Mycobacterium tuberculosis GlmM and GlmU. Carbohydr Res 2011; 346:1714-20. [DOI: 10.1016/j.carres.2011.05.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 05/17/2011] [Accepted: 05/21/2011] [Indexed: 11/18/2022]
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12
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Zhang GL, Zhang LH, Ye XS. Concise syntheses of selective inhibitors against α-1,3-galactosyltransferase. Org Biomol Chem 2010; 8:5062-8. [PMID: 20820649 DOI: 10.1039/c0ob00042f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several iminosugar-based uridine diphosphate galactose (UDP-Gal) mimetics 1-4 including d- and l-epimers were designed and synthesized by concise routes, and these synthetic compounds were evaluated for the inhibition of α-1,3- and β-1,4-galactosyltransferases in vitro. The experimental data demonstrated that l-epimer 2 displayed the strongest inhibitory activity with moderate selectivity against α-1,3-galactosyltransferase.
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Affiliation(s)
- Guo-Liang Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, and School of Pharmaceutical Sciences, Peking University, Xue Yuan Road #38, Beijing 100191, China
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Synthesis of 2-deoxy-hexopyranosyl derivatives of uridine as donor substrate analogues for glycosyltransferases. Bioorg Chem 2009; 37:211-6. [PMID: 19765794 DOI: 10.1016/j.bioorg.2009.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 07/30/2009] [Accepted: 08/11/2009] [Indexed: 11/24/2022]
Abstract
A series of 2-deoxy-hexopyranosyl derivatives of uridine have been synthesized as analogues of UDP-sugar. These compounds were tested as inhibitors against bovine beta-1,4-galactosyltransferase I in fluorescent assays and showed no significant inhibition.
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Satomaa T, Heiskanen A, Leonardsson I, Angström J, Olonen A, Blomqvist M, Salovuori N, Haglund C, Teneberg S, Natunen J, Carpén O, Saarinen J. Analysis of the human cancer glycome identifies a novel group of tumor-associated N-acetylglucosamine glycan antigens. Cancer Res 2009; 69:5811-9. [PMID: 19584298 DOI: 10.1158/0008-5472.can-08-0289] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The cell surface is covered by a dense layer of protein- and lipid-linked glycans. Although it has been known that distinct glycan structures are associated with cancer, the whole spectrum of cancer-associated glycans has remained undiscovered. In the present study, we analyzed the protein-linked cancer glycome by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric glycan profiling of cancer patient tissue samples. In lung cancer, we detected accumulation of a novel group of tumor-associated glycans. These protein-linked glycans carried abnormal nonreducing terminal beta-N-acetyl-D-glucosamine (GlcNAc) residues. A similar phenomenon was also detected in structural analyses of tumor-derived glycosphingolipids. This showed that glycan biosynthesis may dramatically change in cancer and that direct glycome analysis can detect the resulting marker glycans. Based on the structural knowledge, we further devised a covalent labeling technique for the detection of GlcNAc-expressing tumors with a specific transferase enzyme. In normal tissues, terminal GlcNAc antigens are capped by galactosylation. Similarly to common cancer-associated glycan antigens T, Tn, and sialyl-Tn, the newly discovered GlcNAc antigens result from incomplete glycosylation. In conclusion, the identified terminal GlcNAc glycans should be recognized as a novel class of tumor markers.
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16
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Benito D, Matheu MI, Morère A, Díaz Y, Castillón S. Towards the preparation of 2″-deoxy-2″-fluoro-adenophostin A. Study of the glycosylation reaction. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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17
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Brown JR, Crawford BE, Esko JD. Glycan antagonists and inhibitors: a fount for drug discovery. Crit Rev Biochem Mol Biol 2008; 42:481-515. [PMID: 18066955 DOI: 10.1080/10409230701751611] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glycans, the carbohydrate chains of glycoproteins, proteoglycans, and glycolipids, represent a relatively unexploited area for drug development compared with other macromolecules. This review describes the major classes of glycans synthesized by animal cells, their mode of assembly, and available inhibitors for blocking their biosynthesis and function. Many of these agents have proven useful for studying the biological activities of glycans in isolated cells, during embryological development, and in physiology. Some are being used to develop drugs for treating metabolic disorders, cancer, and infection, suggesting that glycans are excellent targets for future drug development.
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Hartman MC, Jiang S, Rush JS, Waechter CJ, Coward JK. Glycosyltransferase mechanisms: impact of a 5-fluoro substituent in acceptor and donor substrates on catalysis. Biochemistry 2007; 46:11630-8. [PMID: 17883281 PMCID: PMC2556460 DOI: 10.1021/bi700863s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In glycosyltransferase-catalyzed reactions a new carbohydrate-carbohydrate bond is formed between a carbohydrate acceptor and the carbohydrate moiety of either a sugar nucleotide donor or lipid-linked saccharide donor. It is currently believed that most glycosyltransferase-catalyzed reactions occur via an electrophilic activation mechanism with the formation of an oxocarbenium ion-like transition state, a hypothesis that makes clear predictions regarding the charge development on the donor (strong positive charge) and acceptor (minimal negative charge) substrates. To better understand the mechanism of these enzyme-catalyzed reactions, we have introduced a strongly electron-withdrawing group (fluorine) at C-5 of both donor and acceptor substrates in order to explore its effect on catalysis. In particular, we have investigated the effects of the 5-fluoro analogues on the kinetics of two glycosyltransferase-catalyzed reactions mediated by UDP-GlcNAc:GlcNAc-P-P-Dol N-acetylglucosaminyltransferase (chitobiosyl-P-P-lipid synthase, CLS) and beta-N-acetylglucosaminyl-beta-1,4 galactosyltransferase (GalT). The 5-fluoro group has a marked effect on catalysis when inserted into the UDP-GlcNAc donor, with the UDP(5-F)-GlcNAc serving as a competitive inhibitor of CLS rather than a substrate. The (5-F)-GlcNAc beta-octyl glycoside acceptor, however, is an excellent substrate for GalT. Both of these results support a weakly associative transition state for glycosyltransferase-catalyzed reactions that proceed with inversion of configuration.
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Affiliation(s)
- Matthew C.T. Hartman
- Departments of Chemistry and Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1055
| | - Songmin Jiang
- Department of Molecular & Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0001
| | - Jeffrey S. Rush
- Department of Molecular & Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0001
| | - Charles J. Waechter
- Department of Molecular & Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0001
| | - James K. Coward
- Departments of Chemistry and Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1055
- To whom correspondence should be addressed: Phone: 734-936-2843. FAX: 734-647-4865. E-mail:
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Dolhem F, Al Tahli F, Lièvre C, Demailly G. Efficient Synthesis of 1,2,3-Triazole-Fused Bicyclic Compounds from Aldoses. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500451] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Nyffeler PT, Durón SG, Burkart MD, Vincent SP, Wong CH. Selectfluor: Mechanismen und Anwendungen. Angew Chem Int Ed Engl 2004. [DOI: 10.1002/ange.200400648] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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21
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Nyffeler PT, Durón SG, Burkart MD, Vincent SP, Wong CH. Selectfluor: Mechanistic Insight and Applications. Angew Chem Int Ed Engl 2004; 44:192-212. [PMID: 15578736 DOI: 10.1002/anie.200400648] [Citation(s) in RCA: 462] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The replacement of hydrogen atoms with fluorine substituents in organic substrates is of great interest in synthetic chemistry because of the strong electronegativity of fluorine and relatively small steric footprint of fluorine atoms. Many sources of nucleophilic fluorine are available for the derivatization of organic molecules under acidic, basic, and neutral conditions. However, electrophilic fluorination has historically required molecular fluorine, whose notorious toxicity and explosive tendencies limit its application in research. The necessity for an electrophilic fluorination reagent that is safe, stable, highly reactive, and amenable to industrial production as an alternative to very hazardous molecular fluorine was the inspiration for the discovery of selectfluor. This reagent is not only one of the most reactive electrophilic fluorinating reagents available, but it is also safe, nontoxic, and easy to handle. In this Review we document the many applications of selectfluor and discuss possible mechanistic pathways for its reaction.
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Affiliation(s)
- Paul T Nyffeler
- Department of Chemistry and Skaggs Institute for Chemical Biology, Scripps Research Institute, 10550 North Torrey Pines Road, BCC 357, La Jolla, California 92037, USA
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Tripathi S, Singha K, Achari B, Mandal SB. In situ 1,3-dipolar azide cycloaddition reaction: synthesis of functionalized d-glucose based chiral piperidine and oxazepine analogues. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.04.036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Elhalabi J, Rice KG. Thiosugar nucleotide analogs: synthesis of 5'-(2,3,4-tri-O-acetyl-6-S-acetyl-6-thio-alpha-D-galactopyranosyl diphosphate). Carbohydr Res 2002; 337:1935-40. [PMID: 12433459 DOI: 10.1016/s0008-6215(02)00210-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis of a novel analog of uridine diphosphate galactose (UDP-Gal) is described. A sulfur atom was inserted into the 6-position of galactose to give uridine 5'-(2,3,4-tri-O-acetyl-6-S-acetyl-6-thio-alpha-D-galactopyranosyl diphosphate). This peracetylated thiol analogue of UDP-Gal has been synthesized in nine steps starting from methyl alpha-D-galactopyranoside in an overall yield of 3%.
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Affiliation(s)
- Jordan Elhalabi
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109-1065, USA
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Hartman MCT, Coward JK. Synthesis of 5-fluoro N-acetylglucosamine glycosides and pyrophosphates via epoxide fluoridolysis: versatile reagents for the study of glycoconjugate biochemistry. J Am Chem Soc 2002; 124:10036-53. [PMID: 12188668 DOI: 10.1021/ja0127234] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Numerous carbohydrate-processing enzymes facilitate catalysis via stabilization of positive charges on or near the C-1, C-4, C-5, or C-6 positions. Substrate analogues differing only in the substitution of a fluorine for the axial C-5 hydrogen would possess reduced electron density at these positions and could be useful mechanistic probes of these enzymes. Introduction of this 5-fluoro substituent after radical halogenation was problematic because of the incompatibility of many protecting groups to the radical halogenation and the instability of the subsequent 5-fluoro hexosamines. Thus, to allow easy access to a wide variety of 5-fluoro glycosides and glycosyl phosphates, a versatile method for the introduction of the 5-fluoro group has been developed, the key step being the fluoridolysis of C-5, 6 epoxides. By use of this method, two fluorinated carbohydrates, uridine 5'-diphospho-5-fluoro-N-acetylglucosamine and octyl 5-fluoro-N-acetylglucosamine, have been synthesized. Initial biochemical investigations of these compounds show that 5-fluoro analogues are useful probes of transition-state charge development in several enzyme-catalyzed reactions.
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25
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Elhalabi J, Rice KG. Thiosugar nucleotide analogues: synthesis of uridine 5'-(2,3,6-tri-O-acetyl-4-S-acetyl-4-thio-alpha-D-galactopyranosyl diphosphate). Carbohydr Res 2001; 335:159-65. [PMID: 11578632 DOI: 10.1016/s0008-6215(01)00228-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The synthesis of a novel uridine diphosphate galactose (UDP-Gal) analog, (UDP-2,3,6-tri-O-acetyl-4-S-acetyl-4-thio-alpha-D-galactopyranose) (10) is described. Compound 10 contains a sulfur in the place of oxygen at the 4-position of the galactose moiety. Compound 10 represents a protected form of a novel sugar nucleotide analog that can potentially be used during chemoenzymatic synthesis to modify complex oligosaccharides.
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Affiliation(s)
- J Elhalabi
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109-1065, USA
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26
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Zhang Q, Liu H. Mechanistic investigation of UDP-galactopyranose mutase from Escherichia coli using 2- and 3-fluorinated UDP-galactofuranose as probes. J Am Chem Soc 2001; 123:6756-66. [PMID: 11448178 DOI: 10.1021/ja010473l] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The galactofuranose moiety found in many surface constituents of microorganisms is derived from UDP-D-galactopyranose (UDP-Galp) via a unique ring contraction reaction catalyzed by UDP-Galp mutase. This enzyme, which has been isolated from several bacterial sources, is a flavoprotein. To study this catalysis, the cloned Escherichia coli mutase was purified and two fluorinated analogues, UDP-[2-F]Galf (9) and UDP-[3-F]Galf (10), were chemically synthesized. These two compounds were found to be substrates for the reduced UDP-Galp mutase with the Km values determined to be 65 and 861 microM for 9 and 10, respectively, and the corresponding kcat values estimated to be 0.033 and 5.7 s(-1). Since the fluorine substituent is redox inert, a mechanism initiated by the oxidation of 2-OH or 3-OH on the galactose moiety can thus be firmly ruled out. Furthermore, both 9 and 10 are poorer substrates than UDP-Galf, and the rate reduction for 9 is especially significant. This finding may be ascribed to the inductive effect of the 2-F substituent that is immediately adjacent to the anomeric center, and is consistent with a mechanism involving formation of oxocarbenium intermediates or transition states during turnover. Interestingly, under nonreducing conditions, compounds 9 and 10 are not substrates, but instead are inhibitors for the mutase. The inactivation by 10 is time-dependent, active-site-directed, and irreversible with a K(I) of 270 microM and a k(inact) of 0.19 min(-1). Since the K(I) value is similar to Km, the observed inactivation is unlikely a result of tight binding. To our surprise, the inactivated enzyme could be regenerated in the presence of dithionite, and the reduced enzyme is resistant to inactivation by these fluorinated analogues. It is possible that reduction of the enzyme-bound FAD may induce a conformational change that facilitates the breakdown of the putative covalent enzyme-inhibitor adduct to reactivate the enzyme. It is also conceivable that the reduced flavin bears a higher electron density at N-1, which may play a role in preventing the formation of the covalent adduct or facilitating its breakdown by charge stabilization of the oxocarbenium intermediates/transition states. Clearly, this study has led to the identification of a potent inactivator (10) for this enzyme, and study of its inactivation has also shed light on the possible mechanism of this mutase.
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Affiliation(s)
- Q Zhang
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, Texas 78712, USA
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27
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Zhang Y, Wang PG, Brew K. Specificity and mechanism of metal ion activation in UDP-galactose:beta -galactoside-alpha -1,3-galactosyltransferase. J Biol Chem 2001; 276:11567-74. [PMID: 11133981 DOI: 10.1074/jbc.m006530200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
UDP-galactose:beta-galactosyl-alpha1,3-galactosyltransferase (alpha3GT) catalyzes the synthesis of galactosyl-alpha-1,3-beta-galactosyl structures in mammalian glycoconjugates. In humans the gene for alpha3GT is inactivated, and its product, the alpha-Gal epitope, is the target of a large fraction of natural antibodies. alpha3GT is a member of a family of metal-dependent-retaining glycosyltransferases that includes the histo blood group A and B enzymes. Mn(2+) activates the catalytic domain of alpha3GT (alpha3GTcd), but the affinity reported for this ion is very low relative to physiological levels. Enzyme activity over a wide range of metal ion concentrations indicates a dependence on Mn(2+) binding to two sites. At physiological metal ion concentrations, Zn(2+) gives higher levels of activity and may be the natural cofactor. To determine the role of the cation, metal activation was perturbed by substituting Co(2+) and Zn(2+) for Mn(2+) and by mutagenesis of a conserved D(149)VD(151) sequence motif that is considered to act in cation binding in many glycosyltransferases. The aspartates of this motif were found to be essential for activity, and the kinetic properties of a Val(150) to Ala mutant with reduced activity were determined. The results indicate that the cofactor is involved in binding UDP-galactose and has a crucial influence on catalytic efficiency for galactose transfer and for the low endogenous UDP-galactose hydrolase activity. It may therefore interact with one or more phosphates of UDP-galactose in the Michaelis complex and in the transition state for cleavage of the UDP to galactose bond. The DXD motif conserved in many glycosyltransferases appears to have a key role in metal-mediated donor substrate binding and phosphate-sugar bond cleavage.
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Affiliation(s)
- Y Zhang
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33101, USA
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28
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Barlow JN, Blanchard JS. Enzymatic synthesis of UDP-(3-deoxy-3-fluoro)-D-galactose and UDP-(2-deoxy-2-fluoro)-D-galactose and substrate activity with UDP-galactopyranose mutase. Carbohydr Res 2000; 328:473-80. [PMID: 11093703 DOI: 10.1016/s0008-6215(00)00135-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The novel UDP-sugar uridine 5'-(3-deoxy-3-fluoro-D-galactopyranosyl diphosphate) (1) and UDP-(2-deoxy-2-fluoro)-D-galactose (2) have been prepared enzymatically and tested as substrate analogues for the enzyme UDP-galactopyranose mutase (UDP-Galp mutase EC 5.4.99.9). Turnover of both 1 and 2 by UDP-Galp mutase was observed by HPLC and 19F NMR. The HPLC elution profile and 19F chemical shift of the products are consistent with the formation of the predicted furanose forms of 1 and 2. The Km values for compounds 1 and 2 were similar to those of the natural substrate UDP-Galp (0.26 mM for 1, 0.2 mM for 2, and 0.6 mM for UDP-Galp), but the values for kcat were substantially different (1.6/min for 1, 0.02/min for 2, and 1364/min for UDP-Galp). A correlation was also observed between the equilibrium yield of product formed during turnover of UDP-sugar by UDP-Galp mutase (UDP-Galp, compound 1 or compound 2), and the amount of furanose present for the free sugar at thermal equilibrium in aqueous solution, using 1H and 19F NMR spectroscopy. The implications of these results to the mechanism of the unusual enzymatic reaction are discussed.
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Affiliation(s)
- J N Barlow
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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29
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Abstract
The high-resolution X-ray crystal structures of a new form of bacteriophage T4 beta-glucosyltransferase, Escherichia coli MurG, Bacillus subtilis SpsA, bovine beta-1,4-galactosyltransferase 1 and rabbit N-acetylglucosaminyltransferase I have now been solved. These glycosyltransferase structures have provided the first detailed view of the structural basis of catalysis, as well as new insight into glycosyltransferase classification.
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Affiliation(s)
- U M Unligil
- Departments of Molecular and Medical Genetics and Biochemistry, University of Toronto, Ontario, M5S 1A8, Toronto, Canada
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30
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31
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Burkart MD, Vincent SP, Düffels A, Murray BW, Ley SV, Wong CH. Chemo-enzymatic synthesis of fluorinated sugar nucleotide: useful mechanistic probes for glycosyltransferases. Bioorg Med Chem 2000; 8:1937-46. [PMID: 11003139 DOI: 10.1016/s0968-0896(00)00139-5] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An effective procedure for the synthesis of 2-deoxy-2-fluoro-sugar nucleotides via Select fluor-mediated electrophilic fluorination of glycals with concurrent nucleophilic addition or chemo-enzymatic transformation has been developed, and the fluorinated sugar nucleotides have been used as probes for glycosyltransferases, including fucosyltransferase III, V, VI, and VII, and sialyl transferases. In general, these fluorinated sugar nucleotides act as competitive inhibitors versus sugar nucleotide substrates and form a tight complex with the glycosyltransferase.
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Affiliation(s)
- M D Burkart
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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32
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33
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Zhang Y, Malinovskii VA, Fiedler TJ, Brew K. Role of a conserved acidic cluster in bovine beta1,4 galactosyltransferase-1 probed by mutagenesis of a bacterially expressed recombinant enzyme. Glycobiology 1999; 9:815-22. [PMID: 10406847 DOI: 10.1093/glycob/9.8.815] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The truncated catalytic domain of bovine beta1,4 galactosyltransferase-1 was expressed as inclusion bodies in E.coli and folded to generate 10-15 mg of active enzyme per liter of bacterial culture after extraction and purification under denaturing conditions. Mutations were introduced to investigate the roles of Trp312, Asp318, and Asp320, components of a highly conserved region of sequence in all known beta4GT-1 homologues that includes a cluster of acidic residues. Near and far UV CD spectra of the mutants indicate that the substitutions did not perturb the secondary and tertiary structure of beta4GT-1, and steady state kinetic studies indicate only minor effects on the response to an essential metal cofactor. However substitutions for the two aspartyl residues result in a reduction in catalytic efficiency of a magnitude that suggests they are important for catalysis. It seems possible that this anionic center may act in stabilizing a carbocation formed from the galactose component of the donor substrate in the transition state, reflecting a common reaction mechanism for beta-galactosyltransferase reactions.
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Affiliation(s)
- Y Zhang
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, FL 33101, USA
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34
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Vincent SP, Burkart MD, Tsai CY, Zhang Z, Wong CH. Electrophilic Fluorination−Nucleophilic Addition Reaction Mediated by Selectfluor: Mechanistic Studies and New Applications. J Org Chem 1999; 64:5264-5279. [DOI: 10.1021/jo990686h] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
It has been shown that all selectins recognize the carbohydrate epitopes sialyl Lewis(x) and sialyl Lewis(a). For the establishment of the structure-activity relationship, the efficient synthesis of these tetrasaccharides and derivatives is therefore of vital interest. The glycosyl transferase-mediated approach is summarized with emphasis on the use of modified acceptors and modified sugar-nucleotide donors. A survey of the involved enzymes: beta(1-3) and beta(1-4)galactosyl transferases, alpha(2-3)sialyl transferase, FucT III and FucT VI reveals that the enzymatic synthesis is highly efficient for the rapid preparation of sialyl Lewis(x)- and sialyl Lewis(a)-derivatives.
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Affiliation(s)
- B Ernst
- University of Basel, Institute of Molecular Pharmacy, Switzerland.
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36
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Takayama S, Chung SJ, Igarashi Y, Ichikawa Y, Sepp A, Lechler RI, Wu J, Hayashi T, Siuzdak G, Wong CH. Selective inhibition of beta-1,4- and alpha-1,3-galactosyltransferases: donor sugar-nucleotide based approach. Bioorg Med Chem 1999; 7:401-9. [PMID: 10218835 DOI: 10.1016/s0968-0896(98)00249-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A combined rational and library approach was used to identify bisphosphonates (IC50 = 20 microM) and galactose type 1-N-iminosugar (IC50=45 microM) as novel motifs for selective inhibition of beta-1,4-galactosyltransferase (beta-1,4-GalT) and alpha-1,3-galactosyltransferase (alpha-1,3-GalT), respectively. Our results demonstrate that, though these two galactosyltransferases both utilize the same donor sugar-nucleotide (UDP-Gal), the difference in their mechanisms can be utilized to design donor sugar or nucleotide analogues with inhibitory activities selective for only one of the galactosyltransferases. Investigation of beta-1,4-GalT inhibition using UDP-2-deoxy-2-fluorogalactose (UDP-2-F-Gal), UDP, and bisphosphonates, also led to the observation of metal dependent inhibition of beta-1,4-GalT. These observations and the novel inhibitor motifs identified in this study pave the way for the design and identification of even more potent and selective galactosyltransferase inhibitors.
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Affiliation(s)
- S Takayama
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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37
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Affiliation(s)
- Chi-Huey Wong
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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38
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Chung SJ, Takayama S, Wong CH. Acceptor substrate-based selective inhibition of galactosyltransferases. Bioorg Med Chem Lett 1998; 8:3359-64. [PMID: 9873734 DOI: 10.1016/s0960-894x(98)00618-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper describes the discovery of glycosyl acceptor analogs as potent and selective inhibitors of alpha-1,3- and beta-1,4-galactosyltransferases. Incorporation of an appropriate aromatic group to the aglycon position of the enzyme's acceptors results in a strong inhibition, representing the first and most potent small uncharged molecules as selective inhibitors of these two enzymes and thus providing a new strategy for the development of selective glycosyltransferase inhibitors.
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Affiliation(s)
- S J Chung
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA
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39
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Wu J, Takayama S, Wong CH, Siuzdak G. Quantitative electrospray mass spectrometry for the rapid assay of enzyme inhibitors. CHEMISTRY & BIOLOGY 1997; 4:653-7. [PMID: 9331404 DOI: 10.1016/s1074-5521(97)90220-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Combinatorial chemistry has become an important method for identifying effective ligand-receptor binding, new catalysts and enzyme inhibitors. In order to distinguish the most active component of a library or to obtain structure-activity relationships of compounds in a library, an efficient quantitative assay is crucial. Electrospray mass spectrometry has become an indispensable tool for qualitatively screening combinatorial libraries and its use for quantitative analysis has recently been demonstrated. RESULTS This paper describes the use of quantitative electrospray mass spectrometry for screening libraries of inhibitors of enzymatic reactions, specifically the enzymatic glycosylation by beta-1,4-galactosyltransferase, which catalyzes the transfer of galactose from uridine-5'-diphosphogalactose to the 4-position of N-acetylglucosamine beta OBn (Bn: benzene) to form N-acetyllactosamine beta OBn. Our mass spectrometric screening approach showed that both nucleoside diphosphates and triphosphates inhibited galactosyltransferase while none of the nucleoside monophosphates, including uridine-5'-monophosphate, showed any inhibition. Additional libraries were generated in which the concentrations of the inhibitors were varied and, using mass spectrometry, uridine-5'-diphosphate-2-deoxy-2-fluorogalactose was identified as the best inhibitor. CONCLUSIONS This report introduces quantitative electrospray mass spectrometry as a rapid, sensitive and accurate quantitative assaying tool for inhibitor libraries that does not require a chromophore or radiolabeling. A viable alternative to existing analytical techniques is thus provided. The new technique will greatly facilitate the discovery of novel inhibitors against galactosyltransferase, an enzyme for which there are few potent inhibitors.
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Affiliation(s)
- J Wu
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA
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