Comparison of catalase activity in different organs of the potato (Solanum tuberosum L.) cultivars grown under field condition and purification by three-phase partitioning

摘要

Catalase (CAT) (H2O2: H2O2 oxidoreductase; EC 1.11.1.6) is capable of directly dismutating moderately reactive H2O2 into H2O and O-2, and is regarded as one of the major enzymatic antioxidants in plants. The CAT isozymes are known to be differentially expressed and regulated. In this study, micropropagated potato plantlets of seven cultivars were grown under field condition with uniform agricultural practices. CAT activities were measured in the crude extracts from different potato organs namely tubers, leaves and stems at different stages of their growth. Relatively higher CAT activity was noticed in the very small actively growing tubers as compared to the other tissues. Cultivar-dependent differences were noticed in terms of the CAT activities which clearly indicated variation with regard to their antioxidative capacities. pH profile, thermostability and storage stability of CAT were examined. A simple and rapid three-phase partitioning (TPP) method worked effectively with regard to purification of CAT from the crude extracts. Both denaturing and non-denaturing PAGE analyses suggested that both the tuber-type and leaf-type CAT are tetrameric in nature and varied in size, possibly referred to the distinct isoforms in potato.