title: Production and characterisation of AoSOX2 from Aspergillus oryzae, a novel flavin-dependent sulfhydryl oxidase with good pH and temperature stability.
abstract: Sulfhydryl oxidases have found application in the improvement of both dairy and baking products due to their ability to oxidise thiol groups in small molecules and cysteine residues in proteins. A genome mining study of the available fungal genomes had previously been performed by our group in order to identify novel sulfhydryl oxidases suitable for industrial applications and a representative enzyme was produced, AoSOX1 from Aspergillus oryzae (Faccio et al. BMC Biochem 11:31, 2010). As a result of the study, a second gene coding for a potentially secreted sulfhydryl oxidase, AoSOX2, was identified in the genome of A. oryzae. The protein AoSOX2 was heterologously expressed in Trichoderma reesei and characterised with regard to both biochemical properties as well as preliminary structural analysis. AoSOX2 showed activity on dithiothreitol and glutathione, and to a lesser extent on D/L-cysteine and beta-mercaptoethanol. AoSOX2 was a homodimeric flavin-dependent protein of approximately 78 kDa (monomer 42412 Da) and its secondary structure presents alpha-helical elements. A. oryzae AoSOX2 showed a significant stability to pH and temperature.
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, Espoo FIN-02044, Finland. greta.faccio@vtt.fi
authors.forename: Greta
authors.initials: G
authors.lastname: Faccio
authors.forename: Kristiina
authors.initials: K
authors.lastname: Kruus
authors.forename: Johanna
authors.initials: J
authors.lastname: Buchert
authors.forename: Markku
authors.initials: M
authors.lastname: Saloheimo
mesh_terms: D001236:Aspergillus oryzae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D005415:Flavins / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D013696:Temperature; D050862:Oxidoreductases Acting on Sulfur Group Donors
chemical_list: D005415:Flavins; D005656:Fungal Proteins; D010088:Oxidoreductases; D050862:Oxidoreductases Acting on Sulfur Group Donors