A novel extracellular peroxidase of the white-rot basidiomycete Coriolus hirsutus

An extracellular peroxidase was purified from the culture filtrate of Corio lus hirsutus and characterized. The protein was purified to electrophoretic homogeneity by using acetone precipitation, gel filtration and ion exchang e chromatographies. The purification of peroxidase was 52.1-fold with an ov erall yield of 26.7%. The native heme protein, pI 3.6, had a molecular mass of 78 kDa as determined by gel filtration and 75 kDa as determined by sodi um dodecyl sulfate polyacrylamide gel electrophoresis. The protein was a mo nomeric glycoprotein with 21% carbohydrate content. The N-terminal amino ac id sequence of the enzyme was significantly different from those of other f ungal peroxidases. The absorption spectra of the native enzyme exhibited a Soret maximum at 409 nm; its intensity was decreased in the oxidized form. The enzyme exhibited a broad temperature optimum between 50 and 65 C and a pH optimum of 3.0. The enzyme catalyzed the oxidation of a variety of usual peroxidase substrates, including monomeric lignin model compounds, but not veratryl alcohol. Under standard assay conditions, the apparent Km Values of enzyme toward ferulic acid and H2O2 were 15.5 and 12.6 mu M, respectivel y. The enzyme was completely inhibited by L-cysteine and sodium bisulfite a nd partially inhibited by potassium cyanide or sodium azide.