The Peroxidase of Dioscorea esculenta: Partial Purification and Characterisation

Abstract

Abstract Dioscorea esculenta. Peroxidase. Ion Exchange Chrom atography. Gel Filtration We isolated two types of peroxidase from the fresh tuber of Dioscorea esculenta using a combination of ion exchange and gel filtration chrom atography. The results showed one type to be neutral and the other to be strongly ionic. The strongly ionic type constitutes 70% of total peroxidase activity in the tissue. The apparent molecular weight of the neutral type is 38 kD a while the anionic type has an apparent molecular weight of 57 kD a. It was possible with the use of gel filtration on Sephadex G-200 followed by FPLC on phenyl superose to purify the lower size POD by a factor of 15, while the larger ionic peroxidase was purified 68 fold com pared to the crude with protein yields of 0.90% and 1.30% respectively. The ionic POD is m ore therm o-stable, has a higher optimum temperature for activity and has a higher ap parent activation energy com pared to the neutral POD from this source.