title: Purification and characterization of an alpha-amylase of Pichia burtonii isolated from the traditional starter "murcha" in Nepal.
abstract: Among more than 20 yeast strains isolated from the traditional starter "murcha" in Nepal, we characterized a yeast that might be involved in saccharification. This strain, identified as Pichia burtonii, produced an extracellular amylolytic enzyme when cultured in the presence of starch in the medium. Since no amylase secreted by P. burtonii has yet been reported, we purified the enzyme and determined its N-terminal amino acid sequence. Together with the results of a hydrolyzing activity assay toward various substrates, it was found to be an alpha-amylase. The purified enzyme, named Pichia burtonii alpha-amylase (PBA), was a glycoprotein with an apparent molecular mass of 51 kDa. Enzyme activity was optimal at pH 5.0 at 40 degrees C. The enzyme retained 80% of its original activity after incubation under the optimal pH condition at 50 degrees C for 30 min. The activity was inhibited by metal ions such as Cd(2+), Cu(2+), Hg(2+), Al(3+), and Zn(2+).
authors.affiliation: Department of Nutritional Science, Faculty of Applied Bio-Science, Tokyo University of Agriculture.
authors.forename: Akiko
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Akiko
authors.initials: A
authors.lastname: Shimizu-Ibuka
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Mura
authors.forename: Sanae
authors.initials: S
authors.lastname: Okada
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Tokue
authors.forename: Soichi
authors.initials: S
authors.lastname: Arai
mesh_terms: D000595:Amino Acid Sequence; D000688:Amylose / Q000378:metabolism; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009390:Nepal; D010843:Pichia / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D000688:Amylose; D000516:alpha-Amylases