Purification and characterization of a novel trimeric and thermotolerant laccase produced from the ascomycete Scytalidium thermophilum strain

A novel laccase from the thermophilic ascomycete fungus Scytalidium thermophilum strain was purified and their biochemical properties were determined. The laccase was purified 8-fold with a specific activity of 139.4 U/mg. This laccase was found to be a homotrimeric protein (subunit molecular-weight of about 28 kDa) with 82 kDa as a total molecular-weight. Its optimum activity pH varied and was substrate dependent. Indeed, it was 5.0 for ABTS and DMP and 6.0 for guaiacol and hydroquinone. Its optimum temperature was 80 °C using DMP as substrate. The enzyme retained 50% of its activity after 120 min of incubation at 70 °C. Under standard assay conditions, laccase Km values were 0.36 mM and 0.26 mM towards 2,6-DMP and ABTS, respectively. It has shown a degrading activity towards a variety of phenolic compounds. The laccase was inhibited by NaN3, DTT, SDS and p-coumarate but not by EDTA, l-Cys, NaF and NaBr. Furthermore, this laccase was stable in the presence of some metal ions.

A novel laccase from the thermophilicascomycete fungus Scytalidiumthermophilum strain was purified and characterized. The single laccase was purified 8-fold to a specific activity of 139.4 U/mg. It was a trimeric protein (subunit molecular-weight of about 28 kDa) with 82 kDa as a total molecular-weight. Its optimum activity pH varied and was substrate dependent. It was 5.0 for ABTS and DMP and 6.0 for guaiacol and hydroquinone. Its optimum temperature was 80 ̊C using DMP as substrate. The enzyme retained 50% of its activity after 120 min of incubation at 70 ̊C. Under standard assay conditions, laccase Km values were 0.36 mM and 0.26 mM towards 2,6-DMP and ABTS, respectively. It has shown a degrading activity towards a variety of phenolic compounds. The laccase was inhibited by NaN3, DTT, SDS and p-coumarate but not EDTA, l-Cys, NaF and NaBr. Furthermore, this laccase was stable in the presence of some metal ions.Figure optionsDownload as PowerPoint slideHighlights
► In this study, we report the purification and characterization of a novel Scytalidium thermophilum laccase.
► This enzyme was trimeric, with a total molecular-weight of 82 kDa, an acidic optimum pH, and an optimum temperature at 80 °C.
► It manifests activity towards a variety of phenolic compounds.
► DMP is the most enzyme sensitive substrate, with a Km of 0.36 mM at pH 5.0 and 25 °C.
► NaN3, DTT, SDS and p-coumarate inhibited laccase. Laccase was stable in the presence of some metal ions.