Laccase isoforms with unusual properties from the basidiomycete Steccherinum ochraceum strain 1833

摘要

To isolate and characterize the laccase isoforms from S. ochraceum 1833 - a new active producer of high extracellular laccase activity. Three laccase isoforms (laccases I, II and III) with 57p"5, 59p"5 and 63 kDa molecular masses respectively were purified from S. ochraceum 1833 and in contrast to the known laccases had strongly pronounced absorption at 611 nm with molar extinction coefficients ranging from 7170 to 7830 molp# l cmp#. All isoforms showed maximal activity with ABTS at low pH ([less-than or equal to]2) and temperatures in the range 70-80pC, were stable for long time of incubation at high temperature (60-80pC) and at pH values ranging from 2 to 6. Laccase II showed a higher activity and wider substrate specificity. N-terminal amino acid sequence analysis of the purified laccase II (VQIGPVTDLH) showed 80% identity with the N-terminal amino acid sequence of laccase from Lentinula edodes [Appl Microbiol Biotechnol60 (2002) 327]. Elevated temperature optima, high thermo- and pH-stabilities, the broad substrate specificity of the isoforms make the laccases from S. ochraceum 1833 a suitable model for biotechnological processes proceeding at high temperatures. For the first time, new basidiomycete strain S. ochraceum was reported as a producer of novel thermostable, pH stable, acidophilic laccases with unusual spectral properties.