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

Abstract

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 enzyme 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 showed optimum activity at pH 3.5 when incubated at 40°C for 5 min. The energy of activation of the enzyme was 15.25 kcal mol −1. The K m for oxalate and V max of the enzyme reaction were 2.16×10 −3 M and 0.18 μmol min −1 ml −1, respectively. Sodium diethyl dithiocarbamate and sodium azide inhibited the enzyme while cysteine caused slight inhibition. Metals and flavins had no effect on the enzyme.