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Molecular adaptation to photo-oxidative stresses in plants.

植物对光氧化胁迫的分子适应。

基本信息

批准号：
63480014
负责人：
ASADA Kozi
金额：
$ 4.42万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

1). Ascorbate peroxidase Two isozymes of ascorbate peroxidase were found in tea leaves. One of them was purified to homogeneity. The enzymatic and molecular properties of this isozyme were characterized in comparison with the other isozyme of ascorbate peroxidase and with guaiacol peroxidases. Ascorbate peroxidases showed differences from guaiacol peroxidase with respect to the specificity of the electron donor; sensitivity to ascorbate removal; sensitivity to thiol reagents; and amino acid composition and amino acid sequence of the amino terminal region. Incubation of ascorbate peroxidase and hydrogen peroxide with p-aminophenol, p-cresol, hydroxyurea, or hydroxyamine results in the inactivation of the enzyme. The radicals of p-aminophenol and hydroxyurea were produced by ascorbate peroxidase as detected by their ESR signals. These signals disappeared upon addition of ascorbate, and the signal characteristic of monodehydroascorbate was found. Thus, ascorbate peroxidase was inactivated by the radicals of p-aminophenol, p-cresol, hydroxyurea and hydroxyamine which are produced by the perocidase reaction, and it is protected from inactivation by ascorbate via the scavenging of the radicals. Thus, these compounds are suicide inhibitors for ascorbatre peroxidase.2). Superoxide dismutase Rice leaves and seed embryo contain four isozymes of CuZn-superoxide dismutase (SOD) and two isozymes of Mn-SOD. CuZn-SOD I is a major enzyme in leaves, but not in embryos or etiolated seedlings. CuZn-SODs II, III and IV were found in the embryos but were also found as minor isozymes in leaves. CuZn-SOD I, II and IV were purified to homogeneity from rice leaves. CuZn-SOD IV was found to be a monomer and the others were dimeric enzymes. CuZn-SOD I which is expressed mainly in leaves is immunologically distinct from the other CuZn-SODs which are mainly expressed in non-photosynthetic tissues.

1）。抗坏血酸过氧化物酶在茶叶中发现了抗坏血酸过氧化物酶的两种同工酶。其中之一被纯化至均质。与抗坏血酸过氧化物酶的其他同工酶和愈创木酚过氧化物酶相比，表征了该同工酶的酶学和分子特性。抗坏血酸过氧化物酶与愈创木酚过氧化物酶在电子供体的特异性方面表现出差异；对抗坏血酸去除的敏感性；对硫醇试剂的敏感性；以及氨基末端区域的氨基酸组成和氨基酸序列。将抗坏血酸过氧化物酶和过氧化氢与对氨基苯酚、对甲酚、羟基脲或羟胺一起孵育会导致酶失活。通过 ESR 信号检测，对氨基苯酚和羟基脲的自由基是由抗坏血酸过氧化物酶产生的。添加抗坏血酸后这些信号消失，并发现单脱氢抗坏血酸的信号特征。因此，抗坏血酸过氧化物酶被过氧化酶反应产生的对氨基苯酚、对甲酚、羟基脲和羟胺自由基失活，并且通过自由基的清除而防止抗坏血酸失活。因此，这些化合物是抗坏血酸过氧化物酶的自杀抑制剂。2)。超氧化物歧化酶水稻叶片和种胚中含有铜锌超氧化物歧化酶（SOD）的四种同工酶和锰超氧化物歧化酶（Mn-SOD）的两种同工酶。 CuZn-SOD I 是叶子中的主要酶，但不是胚胎或黄化幼苗中的主要酶。 CuZn-SOD II、III 和 IV 在胚胎中被发现，但在叶子中也被发现为次要同工酶。 CuZn-SOD I、II 和 IV 从稻叶中纯化至同质。发现 CuZn-SOD IV 是单体，其他酶是二聚体。主要在叶子中表达的 CuZn-SOD I 在免疫学上与主要在非光合组织中表达的其他 CuZn-SOD 不同。