title: Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03.
abstract: An extracellular endoglucanase was isolated from the culture liquid of xylanase producing strain Aspergillus niger B03. The enzyme was purified to a homogenous form, using consecutive ultrafiltration, anion exchange chromatography, and gel filtration. Endoglucanase was a monomer protein with a molecular weight of 26,900 Da determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 28,800 Da determined by gel filtration. The optimal pH and temperature values for the enzyme action were 3.5 and 65 °C respectively. Endoglucanase was stable at 40 °C, pH 3.0 for 210 min. The substrate specificity of the enzyme was determined with carboxymethyl cellulose, filter paper, and different glycosides. Endoglucanase displayed maximum activity in the case of carboxymethyl cellulose, with a Km value of 21.01 mg/mL. The substrate specificity and the pattern of substrate degradation suggested that the enzyme is an endoglucanase. Endoglucanase showed a synergism with endoxylanase in corn cobs hydrolysis.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Food Technologies , 26 Maritza Blvd., 4000 Plovdiv , Bulgaria.
authors.forename: Georgi Todorov
authors.initials: GT
authors.lastname: Dobrev
authors.forename: Boriana Yordanova
authors.initials: BY
authors.lastname: Zhekova
keywords: Aspergillus niger; characterization; endoglucanase; endoxylanase; purification
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