期刊
PLANT AND CELL PHYSIOLOGY
卷 41, 期 10, 页码 1110-1118出版社
OXFORD UNIV PRESS
DOI: 10.1093/pcp/pcd035
关键词
ascorbate; chloroplast; dehydroascorbate reductase; oxidative stress; spinach
Green leaves of plants require the high-level activity that can regenerate ascorbate during photosynthesis, One of such enzyme is dehydroascorbate reductase (DHAR), but the molecular and enzymological properties of the enzyme remain to be fully characterized. In this study, we showed that two major DHAR existed in spinach leaves. The two DHARs occupied at least over 90% of total DHAR activity. The amount of the two DHARS was almost the same. We purified both DHARs from spinach leaves. One form of DHAR originated in chloroplasts; the other occurred in the subcellular compartment other than chloroplasts, The chloroplast DHAR had K-m values of 70 muM and 1.1 mM for dehydroascorbate and reduced glutathione, respectively, The specific activity of the purified enzyme corresponded to 360 mu mol of ascorbate formed per milligram of protein per minute. These properties were quite different from those of trypsin inhibitor, which has been reported to be the plastid DHAR. The other DHAR had the very similar properties to those of chloroplast DHAR. Chloroplast and the other DHARs functioned as a monomer with molecular masses of 26 kDa and 25 kDa, respectively. cDNA for the chloroplast DHAR was cloned with the determined amino-terminal amino acid sequence, The primary sequence predicted from the cDNA. included the plastid-targeting sequence, Finally, the significance of chloroplast DHAR in the regeneration of ascorbate is discussed.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据