Detection of an oxalate oxidase in grain Sorghum roots

Abstract

An oxalate oxidase (EC 1.2.3.4) was detected in 15 000 g supernatant of 10-day-old roots of grain sorghum variety CSH-5. The enzyme showed optimal activity at pH 5 and 40° and required five min incubation. The enzyme was strongly inhibited by EDTA and diethyldithiocarbamate. The activity of the dialysed enzyme could be restored by adding Cu 2+ only. Cu 2+ specific chelator partly reversed the stimulation caused by Cu 2+. Flavins had almost no effect on dialysed enzyme. The enzyme was inhibited both by sulphydryl reagents and —SH group blocking agents which was reversed by addition of Cu 2+. The possibility of sulphydryl-copper ion complex at the active centre of the enzyme is discussed.