title: Purification and characterization of a novel salt-tolerant protease from Aspergillus sp. FC-10, a soy sauce koji mold.
abstract: A novel salt-tolerant protease produced by Aspergillus sp. FC-10 was purified to homogeneity through anion-exchange chromatography, preparative isoelectric-focusing electrophoresis, and gel filtration chromatography, with an overall recovery of 12.7%. This protease demonstrated an optimum pH range of 7.0-9.0 for activity, with a stable pH range of 5.0-9.0. The optimum process temperature at pH 7.0 was 65 degrees C. The enzyme has a molecular mass of 28 kDa and was deduced as a monomer with an isoelectric point of 3.75. Enzyme activity was strongly inhibited by 5 mM of HgCl(2) and FeCl(3), and significantly inhibited by 5 mM of CuSO(4), FeSO(4), and MnCl(2). The activity of this purified protease was inhibited by Na(2).EDTA; however, leupeptin, pepstatin A, PMSF, and E-64 did not affect the activity. Based on the N-terminal amino acid sequence and amino acid composition, this purified protease should be classified as a member of the deuterolysin family.
authors.affiliation: Graduate Institute of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: N W
authors.initials: NW
authors.lastname: Su
authors.forename: M H
authors.initials: MH
authors.lastname: Lee
mesh_terms: D001230:Aspergillus / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D010450:Endopeptidases / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism*; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008670:Metals / Q000737:chemistry / Q000494:pharmacology; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000494:pharmacology; D012492:Salts / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
chemical_list: D008670:Metals; D011480:Protease Inhibitors; D012492:Salts; D012965:Sodium Chloride; D010450:Endopeptidases