title: Characterization of acidic protease from Aspergillus niger BCRC 32720.
abstract: An acid protease from the broth of a 24 h cultivated  Aspergillus niger  BCRC 32720 was purified to electrophoretical homogeneity by CM Sepharose FF and Sephacryl S-100 HR chromatographs. The specific activity, purification fold, and yield were 23.29 kU/mg, 2.5, and 24.2%, respectively. Molecular mass (M) and N-terminal amino acid sequence were 47.5 kDa and SKGSAVTT, whereas the pH and temperature optima were at 2.5 and 50 °C, respectively. It was stable at pH 2.0-4.0 or ≤40 °C and activated by Fe(2+) and cysteine, but partially inhibited by phenylmethanesulfonyl fluoride and tosyllysine chloromethyl ketone and highly inhibited by Ag(+), Sn(2+), Fe(3+), Sb(3+), and pepstatin A. It was considered to be an aspartic protease.
authors.affiliation: Department of Seafood Science, National Kaohsiung Marine University, Nan-Tzu, Kaohsiung 81143, Taiwan.
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Yin
authors.forename: Tzu-Hui
authors.initials: TH
authors.lastname: Hsu
authors.forename: Shann-Tzong
authors.initials: ST
authors.lastname: Jiang
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D013696:Temperature
chemical_list: D010450:Endopeptidases