Purification and characterization of an acetyl xylan esterase produced by Streptomyces lividans.
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.
Dupont
C
C
Centre de Recherche en Microbiologie Appliquée, Université du Québec, Laval-des-Rapides, Canada.
Daigneault
N
N
Shareck
F
F
Morosoli
R
R
Kluepfel
D
D
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
D009844:Oligosaccharides; D011994:Recombinant Proteins; D000115:Acetylesterase; C081851:acetylxylan esterase