Physicochemical properties of rhodanese from the kidney of cane rat (Thryonomys swinderianus)

Abstract

We report the properties of partially purified rhodanese, a cyanide detoxifying enzyme isolated from the kidney of the greater cane rat commonly known as grasscutter (Thryonomys swinderianus). T. swinderianus kidney rhodanese had a specific activity of 1.43 µmole/min/mg protein, a fold of 2.31 and a 55% recovery. The apparent K m values of 0.408 and 0.316 mM were obtained for both sodium thiosulphate (Na 2 S 2 O 3) and potassium cyanide (KCN) respectively. Substrate specificity study showed that T. swinderianus rhodanese can use other substrates. The enzyme showed its maximum activity at pH 8.0 and 50°C. The assay for the effect of metal ions showed that the enzyme is not affected or inhibited by metal ions such as Na + , Fe 3+ but inhibited by Hg 2+ . The continued existence of T. swinderianus after consumption of food crops with high cyanogenic glycosides suggests that the animal has a functional cyanide detoxification mechanism.