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Endopeptidases in wheat flag leaves during aging

Gao Ling, Ye Maobing, Zhang Rongxian, Xu Langlai

College of Science,Ministry of China,Nanjing Agricultural University.Nanjing 210095,Jiangsu；China

Abstract

Studies with an activator (DTT) and inhibitors (PMSF, IA and EDTA) have shown that there are at least three kinds of endopeptidases in wheat flag leaves, i.e, thiol-proteinases, serine proteinases and metallo-proteinases. The changes in endopeptidases activity during leaf aging could be divided into two phases. During the first phase, the activity of endopeptidases changed at a low level, but it increased rapidly in the second phase. This trend corresponded to the decline in rate of net photosynthesis and the total soluble protein content. The pH optimum and temperature optimum of wheat leaf endopeptidases are 4.8 and 45 degree C, respectively. Exogenous BA and actidione could prevent the rise of activity of endopeptidases, while cysteine, serine and ABA could enhance it.

Key words: Wheat flag leaf;Photosynthesis;Endopeptidase;Aging

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Citing This Article：

Gao Ling, Ye Maobing, Zhang Rongxian, Xu Langlai. Endopeptidases in wheat flag leaves during aging. Acta Physiol Sin 1998; 50 (2): (in Chinese with English abstract).