Purification and properties of a membrane bound oxalate oxidase from Amaranthus leaves

A membrane bound oxalate oxidase has been purified to apparent homogeneity from mature leaves of the wild herb Amaranthus spinosus. The M-r of the enz yme was ca. 130 kDa by Sephadex G-200 gel filtration and 65 kDa by SDS disc electrophoresis indicating two subunits of identical M-r. The enzyme showe d optimum activity at pH 3.5 when incubated at 40 degrees C for 5 min. The energy of activation of the enzyme was 15.25 kcal mol(-1). The K-m for oxal ate and V-max of the enzyme reaction were 2.16 x 10(-3) M and 0.18 mu mol m in(-1) ml(-1), respectively. Sodium diethyl dithiocarbamate and sodium azid e inhibited the enzyme while cysteine caused slight inhibition. Metals and flavins had no effect on the enzyme. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.