title: Production, purification and characterization of an extracellular alpha-amylase enzyme isolated from Aspergillus flavus.
abstract: Filamentous fungi isolated from cereals were screened for their ability to produce alpha-amylase (1,4-alpha-glucan glucanohydrolase, EC 3.2.1.1). A selected strain identified as Aspergillus flavus showed high enzymatic activity. A single extracellular alpha-amylase was purified to homogeneity by a starch adsorption method. The molecular weight (M(r)) of the A. flavus alpha-amylase was approximately 75,000 +/- 3,000 by polyacrylamide gel electrophoresis (PAGE) and that of the subunit was approximately 75,000 +/- 3000 SDS-PAGE. The optimal activity of the purified enzyme was achieved at pH 7.0 and 30 degrees C. K+ ions increased the alpha-amylase activity, but Mg2+ did not greatly affect enzyme activity. Mn2+, Zn2+, Cu2+ and Fe3+ ions strongly inhibited the enzyme activity. The products of hydrolysis of native starch by the A. flavus enzyme were mainly glucose as well as unidentified oligosaccharides.
authors.affiliation: Department of Botany, Faculty of Science, Tanta University, Egypt.
authors.forename: A M
authors.initials: AM
authors.lastname: Abou-Zeid
mesh_terms: D001231:Aspergillus flavus / Q000201:enzymology*; D008970:Molecular Weight; D000516:alpha-Amylases / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000516:alpha-Amylases