Autori: Augustin C. Mot, Marcel Parvu, Grigore Damian,Zsuzsanna Darula, Katalin F. Medzihradszky, Balazs Brem, Radu Silaghi-Dumitrescu
Editorial: Elsevier, Process Biochemistry, 47( 6), p.968–975, 2012.
Reported here are the production, purification and characterization of a laccase from the phytophathogenic fungus Sclerotinia sclerotiorum. This laccase is identified by mass spectrometry with a sequence coverage of 74.9% (458/577 AA) revealing that the protein is identical or highly homologous to a predicted oxidoreductase from this species (A7EM18 in the Uniprot database); the closest homologous protein previously isolated from a fungus is the Melanocarpus albomyces, with only 35% identity. The UV-vis spectral features of this laccase classify it as a “yellow” one. The EPR spectrum nevertheless demonstrates resemblance to blue laccases–including the type 1 center not detectable in UV vis spectra. The presence of type 3 coppers was proven by fluorescence spectrum and by 330 nm band in UV-vis. The purified laccase has an apparent molecular mass of 70 kDa and appears as a monomer. The values of KM and kcat were determined for ABTS, 2,6 dimethoxyphenol, p-phenylenediamine and guaicol and are typical of a laccase. The optimal pH value is around 4 except for ABTS, for which activity is linearly increasing with acidity. The high laccase activity in liquid culture makes Sclerotinia sclerotiorum a useful source of laccase for practical applications
Cuvinte cheie: Sclerotinia sclerotiorum; Yellow laccase; EPR spectroscopy; UV-vis spectroscopy