B.A.GANAP, A. MA SOOD, M.A. ZARGAR AND SYED M. BASHIR
Abstract
The enzyme sulphite oxidase (EC 1.8.3.1), believed to be responsible for the detoxifaction of sulphur dioxide/ sulphite to sulphate, till date has been purified and characterized from a variety of animal, microbial and plant sources. The enzyme obtained from majority of animal sources has been found to be a homodimer with each subunit having a molecular weight of 55 KDa wheras the ones obtained from plant sources ranges between 27-33 KDa. The prosthetic group associated with the animal and microbial sulphite oxidase is Cytochrome b5 whereas plant sulphite oxidase has been found to contain molybdenum. Stokes readius and frictional ratio of sulphite oxidase obtained from Malva sylvesteris are 2.29 mm and 1.16 nm respectively. The Km value of sulphite oxidase has been found variable ranging from 10-7 to 10-3 M and it shows absorption maxima of 210, 280, 413 and 570 nm with pH stability at 7.8.