ACTIVATION BY ORGANIC-SOLVENTS OF AN ALKALINE THERMOSTABLE PEROXIDASEPARTIALLY PURIFIED FROM RICE HULLS

A thermostable alkaline peroxidase was partially purified from rice hu lls by precipitation in 70% (v/v) isopropanol, anion exchange chromato graphy on a DEAE cellulose column (eluted by 50 mM potassium phosphate , pH 6.0), and gel filtration on a Sephacryl S-200 column. The peroxid ase (RHP) showed a maximum activity at a slightly alkaline condition, between pH 7 and 8, for the oxidation of guaiacol in the presence of 0 .2 mM H2O2. The half life time for the inactivation of RHP at 68 degre es C was 168 min nearly six times that of horseradish peroxidase (HRP) at the same temperature. Dioxane enhanced the activity of RHP but dec reased that of HRP.