Presence of sulphite oxidase in yam leaves

Abstract

Yam chloroplast possesses sulphite oxidase activity when coupled with ferricyanide reduction and oxygen consumption.  This activity is associated with thylakoid and is solubilized using non-ionic biological detergent.  pH and temperature dependence of the enzyme indicate that it is an intrinsic membrane protein.  This enzyme is insensitive to radical scavengers (mannitol, mannose and fructose) and catalase but is inhibited by high concentration of superoxide dismutase.  Sulphite oxidation is not induced by photosynthetic electron transport system but is achieved by membrane bound sulphite oxidase activity.  The kinetic parameters of the enzyme were compared with those of other sulphite oxidases