Characterization of soluble rifamycin oxidase from Curvularia lunata var. aeria.

Curvularia lunata var. aeria was grown on yeast extract, peptone and carboxymethylcellulose (YPC) medium for the production of extracellular rifamycin oxidase. The enzyme was partially purified through a Sephadex G-75 column. The half lives of rifamycin oxidase at 30 degrees and 40 degrees C were 9 d and 100 min, respectively. The activation and deactivation energies of the partially purified enzyme, calculated from Arrhenius plots, were 5.80 and 35.10 kcal mol-1, respectively. The enzyme exhibited a Km (rifamycin B) value of 0.67 mmol l-1 and a Vmax of 11 mumol h-1.ml. Three metal ions, Fe2+, Ag+ and Hg2+, inhibited the enzyme in the 10-20 mmol l-1 metal ion concentration range. Catalytic activity was not affected by the chelating agent, EDTA.