A study of peroxidase and amylase isoenzymes in different radish cultivarsduring winter storage

The changes in activities of soluble peroxidase (EC 1.11.1.7; POD) and amyl ase (EC 3.2.1.1) and in levels of soluble protein and reducing sugar are in vestigated in three cultivars of radishes (Raphanus Sativus L) in winter st orage for 150 days. It has been shown that the activity of peroxidase incre ases at first and then decreases during the storage. The highest POD activi ty appears on the 90th day. The levels of reducing sugars change similarly. Peroxidase isoenzymes (types and activities) in these radish cultivars are obviously different during the storage. The highest activities of peroxida se Isoenzymes are observed in Xinlimei (XLM) and the lowest in Dihuangying (DHY). The difference between the radish cultivars is also observed in the peroxidase isoenzyme types. Both cationic and anionic peroxidase isoenzymes appear in the radish during storage. The activities and PAGE bands of the amylase isoenzymes decrease with increasing storage time. The activities of amylase are the lowest in the XLM but highest in the DHY. A similar change is found for the levels of soluble protein during the storage: the levels are highest in XLM and lowest in DHY. These results suggest a possible corr elation between the activity of peroxidase and the level of reducing sugar during storage. (C) 2000 Society of Chemical Industry.