title: Purification and characterization of an acetyl xylan esterase produced by Streptomyces lividans.
abstract: The acetyl xylan esterase cloned homologously from Streptomyces lividans [Shareck, Biely, Morosoli and Kluepfel (1995) Gene 153, 105-109] was purified from culture filtrate of the overproducing strain S. lividans IAF43. The secreted enzyme had a molecular mass of 34 kDa and a pI of 9.0. Under the assay conditions with chemically acetylated birchwood xylan the kinetic constants of the enzyme were: specific activity, 715 units/mg, Km 7.94 mg/ml and Vmax 1977 units/mg. Optimal enzyme activity was obtained at 70 degrees C and pH 7.5. Hydrolysis assays with different acetylated substrates showed that the enzyme is specific for deacetylating the O-acetyl group of polysaccharides and is devoid of N-deacetylation activity. Sequential hydrolysis shows that its action is essential for the complete degradation of acetylated xylan by the xylanases of S. lividans.
authors.affiliation: Centre de Recherche en Microbiologie Appliquée, Université du Québec, Laval-des-Rapides, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Dupont
authors.forename: N
authors.initials: N
authors.lastname: Daigneault
authors.forename: F
authors.initials: F
authors.lastname: Shareck
authors.forename: R
authors.initials: R
authors.lastname: Morosoli
authors.forename: D
authors.initials: D
authors.lastname: Kluepfel
mesh_terms: D000115:Acetylesterase / Q000096:biosynthesis / Q000302:isolation & purification* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D015870:Gene Expression; D007700:Kinetics; D008970:Molecular Weight; D009844:Oligosaccharides / Q000096:biosynthesis / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D009844:Oligosaccharides; D011994:Recombinant Proteins; D000115:Acetylesterase; C081851:acetylxylan esterase