Department of Biochemistry and Genetics, The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, Connecticut 06504.
Plant Physiol. 1991 Dec;97(4):1592-5. doi: 10.1104/pp.97.4.1592.
Experiments were conducted with a tobacco (Nicotiana tabacum) mutant with 40 to 50% greater catalase activity than wild type that is associated with a novel form of O(2)-resistant photosynthesis. The apparent K(m) for H(2)O(2) was the same in mutant and wild-type leaf extracts. Tobacco RNAs were hybridized with Nicotiana sylvestris catalase cDNA, and a threefold greater steady-state level of catalase mRNA was found in mutant leaves. Steady-state levels of ribulose-1,5-bisphosphate carboxylase small subunit mRNA were similar in mutant and wild type. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of partially purified catalase showed that the protein concentration in the band corresponding to catalase was higher in the mutant than in the wild type. Separation of leaf catalase proteins by isoelectric focusing revealed the presence of five major bands and one minor band of activity. The distribution of the catalase activity among these forms was similar in mutant and wild type, although the total activity was higher in the mutant in all five major bands. The results indicate that the enhanced catalase activity in mutant leaves is caused by an increase in synthesis of catalase protein and that this trait is mediated at the nucleic acid level.
实验以一种烟草（Nicotiana tabacum）突变体为对象，该突变体的过氧化氢酶活性比野生型高 40%至 50%，与一种新型的 O(2)-抗性光合作用有关。突变体和野生型叶片提取物中的 H(2)O(2)表观 K(m)相同。烟草 RNA 与 Nicotiana sylvestris 过氧化氢酶 cDNA 杂交，发现突变体叶片中过氧化氢酶 mRNA 的稳态水平增加了三倍。突变体和野生型的核酮糖-1,5-二磷酸羧化酶小亚基 mRNA 的稳态水平相似。部分纯化的过氧化氢酶的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示，与过氧化氢酶相对应的条带中的蛋白质浓度在突变体中高于野生型。等电聚焦分离叶片过氧化氢酶蛋白显示存在五种主要带和一种活性较小带。尽管在所有五个主要带中，突变体的总活性更高，但这些形式之间的过氧化氢酶活性分布在突变体和野生型中相似。结果表明，突变体叶片中过氧化氢酶活性的增强是由于过氧化氢酶蛋白合成的增加引起的，这种特性是在核酸水平上介导的。
