Purification and characterization of the main laccase produced by the white-rot fungus Pleurotus pulmonarius on XXXX bran solid state medium.

@entity10694 @entity16376 @entity8863 @entity3281 @entity1324 @entity1626 @entity12682 @entity6514 @entity44400 @entity3505 @entity4627 @entity1098
The wood-degrading fungus Pleurotus pulmonarius produces at least two laccase isoforms, Lcc1 and Lcc2, when grown on @entity3505 bran solid state medium. The main laccase, Lcc2, was purified to apparent electrophoretic homogeneity by using @entity1324 precipitation, anion-exchange chromatography and gel filtration. Lcc2 had been purified 5.9-fold with a yield of 49%. A specific activity of 19750 U/mg protein was found using @entity44400 as a substrate under standard assay conditions. The enzyme is a homodimeric glycoprotein containing 44% glycosilation and an apparent molecular mass of 46 kDa. Type I and type III @entity8863 centers were identified by spectrophotometry. The laccase showed optimal activity at pH 6.2-6.5, 4.0-5.5, and 6.0-8.0 with @entity44400 , @entity16376 and guaiacol as substrates, respectively. For all substrates, the highest oxidation rates were obtained at 50 degrees C. The enzyme was stable over a large range of pH (4.5-8.0) and at temperatures up to 50 degrees C. Under standard assay conditions, the apparent K(M) values were 12, 210 and 550 microM for @entity44400 , @entity16376 and @entity12682 , respectively. Purified Lcc2 was strongly inhibited by @entity4627 , @entity6514 and @entity10694 , and slightly inhibited by @entity3281 and the chelant agents, @entity1098 and EGTA. The enzyme was activated by @entity8863 and it retained a high percentage of its activity in the presence of organic solvents, such as @entity1626 and @entity1324 .
