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Titolo:
Hexuronyl C5-epimerases in alginate and glycosaminoglycan biosynthesis
Autore:
Valla, S; Li, JP; Ertesvag, H; Barbeyron, T; Lindahl, U;
Indirizzi:
Univ Uppsala, Ctr Biomed, Dept Med Biochem & Microbiol, S-75123 Uppsala, Sweden Univ Uppsala Uppsala Sweden S-75123 & Microbiol, S-75123 Uppsala, Sweden CNRS Goemar, Stn Biol Roscoff, UMR 1931, F-29682 Roscoff, France CNRS Goemar Roscoff France F-29682 ff, UMR 1931, F-29682 Roscoff, France Norwegian Univ Sci & Technol, Dept Biotechnol, N-7491 Trondheim, Norway Norwegian Univ Sci & Technol Trondheim Norway N-7491 1 Trondheim, Norway
Titolo Testata:
BIOCHIMIE
fascicolo: 8, volume: 83, anno: 2001,
pagine: 819 - 830
SICI:
0300-9084(200108)83:8<819:HCIAAG>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
URONOSYL C-5 EPIMERASE; HEPARAN-SULFATE PROTEOGLYCANS; MANNURONAN C-5-EPIMERASE GENE; HYDROPHOBIC CLUSTER-ANALYSIS; AZOTOBACTER-VINELANDII; DERMATAN SULFATE; HEPARIN/HEPARAN SULFATE; PSEUDOMONAS-AERUGINOSA; GLUCURONYL C-5; CAPSULAR POLYSACCHARIDE;
Keywords:
epimerase; alginate; heparin; dermatan sulfate;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
55
Recensione:
Indirizzi per estratti:
Indirizzo: Lindahl, U Univ Uppsala, Ctr Biomed, Dept Med Biochem & Microbiol, Box 582, S-75123 Uppsala, Sweden Univ Uppsala Box 582 Uppsala Sweden S-75123 23 Uppsala, Sweden
Citazione:
S. Valla et al., "Hexuronyl C5-epimerases in alginate and glycosaminoglycan biosynthesis", BIOCHIMIE, 83(8), 2001, pp. 819-830

Abstract

The sugar residues in most polysaccharides are incorporated as their corresponding monomers during polymerization. Here we summarize the three known exceptions to this rule, involving the biosynthesis of alginate, and the glycosaminoglycans, heparin/heparan sulfate and dematan sulfate. Alginate is synthesized by brown seaweeds and certain bacteria, while glycosaminoglycans are produced by most animal species. In all cases one of the incorporatedsugar monomers are being C5-epimerized at the polymer level, from D-mannuronic acid to L-guluronic acid in alginate, and from D-glucuronic acid to L-iduronic acid in glycosaminoglycans. Alginate epimerization modulates the mechanical properties of seaweed tissues, whereas in bacteria it seems to serve a wide range of purposes. The conformational flexibility of iduronic acid units in glycosaminoglycans promotes apposition to, and thus functional interactions with a variety of proteins at cell surfaces and in the extracellular matrix. In the bacterium Azotobacter vinelandii the alginates are being epimerized at the cell surface or in the extracellular environment by afamily of evolutionary strongly related modular type and Ca2+-dependent epimerases (AlgEl-7). Each of these enzymes introduces a specific distribution pattern of guluronic acid residues along the polymer chains, explaining the wide structural variability observed in alginates isolated from nature. Glycosaminoglycans are synthesized in the Golgi system, through a series ofreactions that include the C5-epimerization reaction along with extensive sulfation of the polymers. The single, Ca2+-independent, epimerase in heparin/heparan sulfate biosynthesis and the Ca2+-dependent dermatan sulfate epimerase(s) also generate variable epimerization patterns, depending on otherpolymer-modification reactions. The alginate and heparin epimerases appearunrelated at the amino acid sequence level, and have probably evolved through independent evolutionary pathways; however, hydrophobic cluster analysis indicates limited similarity. Seaweed alginates are widely used in industry, while heparin is well established in the clinic as an anticoagulant. (C) 2001 Societe francaise de biochimie et biologic moleculaire/Editions scientifiques et medicales Elsevier SAS. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/01/20 alle ore 13:00:35