Biochemical characterization of a novel laccase from the basidiomycete fungus Cerrena sp. WR1

This study reports a new white-rot fungus Cerrena sp. WR1, identified based on an 18S rDNA sequence, which can secrete extracellular forms of laccase with a maximal activity reaching 202 000 U l^-1 in a 5-l fermenter. A laccase protein, designated Lcc3, was purified and shown to be N-linked glycosylated by PNGase F and liquid chromatography tandem mass spectrometry analyses. The respective full-length cDNA gene (lcc3) of the Lcc3 protein was obtained using polymerase chain reaction-based methods. Kinetic studies showed that the K_m and k_cat of the native Lcc3 were 3.27 μM and 934.6 s^-1 for 2,2′-Azino-bis-(3-ethylbenzthiazoline-6- sulfonic acid), 849.1 μM and 147.9 s^-1 for guaiacol, 392.7 μM and 109.2 s^-1 for 2,6-dimethoxyphenol, and 881 μM and 115.5 s ^-1 for catechol, respectively. The T_m of Lcc3 was determined at 73.9°C and it showed a long t_1/2 (120 min) at 50°C. The laccase was highly ethanol resistant, with 80 of its original activity was detected when incubated in 25 ethanol for 14 days. Furthermore, crude enzyme broth or Lcc3 could degrade lignin in kraft paper (26.5), and showed high decoloration efficiency (90) on synthetic dye Remazol Brilliant Blue R. Together, these data demonstrate that Cerrena sp. WR1 Lcc3 possesses novel biochemical and kinetic properties that may aid its application in industry.