Details

Autor(en) / Beteiligte

• Schneider, Palle
• Caspersen, Mikael B.
• Mondorf, Kristine
• Halkier, Torben
• Skov, Lars K.
• Østergaard, Peter R.
• Brown, Kimberly M.
• Brown, Stephen H.
• Xu, Feng

Titel

Characterization of a Coprinus cinereus laccase

Ist Teil von

• Enzyme and microbial technology, 1999-09, Vol.25 (6), p.502-508

Ort / Verlag

Amsterdam: Elsevier Inc

Erscheinungsjahr

1999

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• A wild-type Coprinus cinereus laccase and its recombinant form expressed in an Aspergillus oryzae host have been purified and characterized. The mature laccase had a molecular mass of 58 kDa by mass spectrometry, an isoelectric point near 4, and two absorption maxima at 278 and 614 nm. Photometric titration with 2,2′-biquinoline showed a Cu/protein(subunit) stoichiometry of ≈4. The electron paramagnetic resonance spectrum showed typical type 1 and type 2 Cu signals, and the circular dichroism showed a typical coordination geometry of the type 1 Cu(II). At pH 5.5, the enzyme had a redox potential of 0.55 V vs. normal hydrogen electrode at its type 1 site. The laccase could oxidize 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) and syringaldazine with optimum pH of 4 and 6.5, respectively. Halides inhibited the laccase. At pH 8.5, the laccase had an optimum temperature between 60°C and 70°C. At the same pH, the laccase had a half-life of >200 or 21.8 min in the presence of 0 or 2 mM H 2O 2, respectively, at 40°C. Mediated by several phenols and phenothiazines, the laccase was able to oxidatively bleach Direct Blue 1 dye at alkaline pH, making it a promising industrial enzyme candidate.