A new basidiomycete, Trametes sp. 420, produced laccase at 6,810 U l(-1) (268 mg, 25.4 U mg(-1) protein for guaiacol) in glucose medium and 7,870 U l(-1) (310 mg) in cellobiose medium with induction by 0.5 mM Cu(2+) and 6 mM o-toluidine. Laccase isozyme E (LacE) was the sole laccase in the fermentation products. It was stable at pH 5-9 and below 70 degrees C over 30 min. The K (m) values of LacE for four substrates (guaiacol ABTS, 2,6-dimethoxyphenol and syringaldazine) varied from 5 to 245 muM. The activity of LacE was strongly inhibited by NaN(3) but not by EDTA or dimethylsulfoxide. LacE at 0.5 U l(-1) could decolorize industrial dyes. The open reading frame of the lacE gene was 2,130 bp and was interrupted by 10 introns. It displayed a high homology to laccases from other fungi.