title: Characterization of a new tyrosinase from Pycnoporus species with high potential for food technological applications.
abstract: OBJECTIVE
  Tyrosinase production by Pycnoporus cinnabarinus and Pycnoporus sanguineus was screened among 20 strains originating from various geographical areas, particularly from tropical environments. The tyrosinase from the most efficient strain was purified and characterized and tested for food additive applications.
  
  
  RESULTS
  Monophenolase and diphenolase activities of tyrosinase were measured from cell lysate from the 20 Pycnoporus strains, for 8-10 days of cultivation. The strain P. sanguineus CBS 614.73 showed the highest productivity (45.4 and 163.6 U g(-1) protein per day for monophenolase and diphenolase respectively). P. sanguineus CBS 614.73 tyrosinase was purified from concentrated cell lysate, anion-exchange, size-exclusion and hydroxyapatite chromatography, with a final yield of 2% and a purification factor of 35-38. The pure enzyme was a monomere with a molecular mass of 45 kDa and it showed four isoforms or isoenzymes with pI between 4.5-5. No N-glycosylation was found. The N-terminal amino acid sequence was IVTGPVGGQTEGAPAPNR. The enzyme was shown to be almost fully active in a pH range of 6-7, in a large temperature range (30-70 degrees C), and was stable below 60 degrees C. The main kinetic constants were determined. The tyrosinase was able to convert p-tyrosol and p-coumaric acid into hydroxytyrosol and caffeic acid, respectively, and it could also catalyse the cross-linking formation of a model protein.
  
  
  CONCLUSIONS
  Among the genus Pycnoporus, known for the production of laccase, the strain P. sanguineus CBS 614.73 was shown to produce one other phenoloxidase, a new monomeric tyrosinase with a specific activity of 30 and 84 U mg(-1) protein for monophenolase and diphenolase respectively.
  
  
  CONCLUSIONS
  This study identified P. sanguineus CBS 614.73 as a potential producer of a tyrosinase which demonstrated effectiveness in the synthesis of antioxidant molecules and in protein cross-linking.
authors.affiliation: UMR 1163 INRA-Université de Provence de Biotechnologie des Champignons Filamenteux, IFR 86 de Biotechnologie Agro-Industrielle de Marseille, Marseille Cedex 09, France.
authors.forename: S
authors.initials: S
authors.lastname: Halaouli
authors.forename: Mi
authors.initials: M
authors.lastname: Asther
authors.forename: K
authors.initials: K
authors.lastname: Kruus
authors.forename: L
authors.initials: L
authors.lastname: Guo
authors.forename: M
authors.initials: M
authors.lastname: Hamdi
authors.forename: J-C
authors.initials: JC
authors.lastname: Sigoillot
authors.forename: M
authors.initials: M
authors.lastname: Asther
authors.forename: A
authors.initials: A
authors.lastname: Lomascolo
mesh_terms: D001483:Base Sequence; D001709:Biotechnology; D005516:Food Microbiology; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism*
chemical_list: D014442:Monophenol Monooxygenase