PURIFICATION AND CHARACTERIZATION OF AN EXTRACELLULAR PEROXIDASE FROMWHITE-ROT FUNGUS PLEUROTUS-OSTREATUS

A peroxidase was purified 98.3-fold from the culture filtrate of Pleur otus ostreatus with an overall yield of 12.4%. The molecular mass dete rmined by gel filtration was found to be approx. 140 kDa. SDS-PAGE rev ealed that the enzyme consists of two identical subunits with a molecu lar mass of approx. 72 kDa. The pI value of this enzyme is approx. 4.3 . The enzyme contains 41% carbohydrate by weight, and aspartic acid an d asparagine (16.8%), and glutamic acid and glutamine (12.0%). The enz yme has the highest affinity toward sinapic acid and affinity towards various phenolic compounds containing methoxyl and p-hydroxyl groups, directly attached to the benzene ring. However, the enzyme does not re act with veratryl alcohol and shows no affinity for nonphenolic compou nds. The optimal reaction pH and temperature are 4.0 and 40-degrees-C, respectively. The catalytic mechanism of the enzymic reaction is of t he Ping-Pong type. The activity of the enzyme is competitively inhibit ed by high concentrations of H2O2 and its K(i) value is 1.70 mM agains t H2O2. This enzyme contains approx. 1 mol of heme per mol of one subu nit of the enzyme. The pyridine hemochrome spectrum of the enzyme indi cates that the heme of P. ostreatus peroxidase is iron protoporphyrin IX. The EPR spectrum of the native peroxidase shows the presence of a high-spin ferric complex with g values at 6.102, 5.643 and 1.991.