title: Purification, partial characterization, and covalent immobilization-stabilization of an extracellular α-amylase from Aspergillus niveus.
abstract: An extracellular amylase secreted by Aspergillus niveus was purified using DEAE fractogel ion exchange chromatography and Sephacryl S-200 gel filtration. The purified protein migrated as a single band in 5 % polyacrylamide gel electrophoresis (PAGE) and 10 % sodium dodecyl sulfate (SDS-PAGE). The enzyme exhibited 4.5 % carbohydrate content, 6.6 isoelectric point, and 60 and 52 kDa molar mass estimated by SDS-PAGE and Bio-Sil-Sec-400 gel filtration column, respectively. The amylase efficiently hydrolyzed glycogen, amylose, and amylopectin. The end-products formed after 24 h of starch hydrolysis, analyzed by thin layer chromatography, were maltose, maltotriose, maltotetraose, and maltopentaose, which classified the studied amylase as an α-amylase. Thermal stability of the α-amylase was improved by covalent immobilization on glyoxyl agarose (half-life of 169 min, at 70 °C). On the other hand, the free α-amylase showed a half-life of 20 min at the same temperature. The optima of pH and temperature were 6.0 and 65 °C for both free and immobilized forms.
authors: Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Monte Alegre, 14.040-901, Ribeirão Preto, SP, Brazil.
authors: Tony Marcio
authors: TM
authors: Silva
authors: André Ricardo de Lima
authors: AR
authors: Damásio
authors: Alexandre
authors: A
authors: Maller
authors: Michele
authors: M
authors: Michelin
authors: Fabio M
authors: FM
authors: Squina
authors: João Atílio
authors: JA
authors: Jorge
authors: Maria de Lourdes Teixeira de Moraes
authors: Mde L
authors: Polizeli
mesh_terms: D000595:Amino Acid Sequence; D000687:Amylopectin / Q000378:metabolism; D000688:Amylose / Q000378:metabolism; D001230:Aspergillus / Q000201:enzymology*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013696:Temperature; D000516:alpha-Amylases / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D006003:Glycogen; D000688:Amylose; D000687:Amylopectin; D000516:alpha-Amylases