PHOTOINACTIVATION OF CATALASE INVITRO AND IN LEAVES
PHOTOINACTIVATION OF CATALASE INVITRO AND IN LEAVES
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DOI：
10.1016/0003-9861(86)90365-6
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发表时间：
1986-12-01
影响因子：
3.9
通讯作者：
ENGEL, S
中科院分区：
文献类型：
--
作者：
FEIERABEND, J;ENGEL, S
用可见光照射对纯化的牛肝过氧化氢酶和分离的完整的黑麦叶片过氧化氢酶进行了体外灭活。在光灭活过程中，纯过氧化氢酶的蛋白质部分没有被切割，但天然酶的电泳迁移率降低，酶结合的大部分血红素被解离。在分离的叶绿体悬浮液中，纯过氧化氢酶或过氧化氢酶的光失活是由叶绿体中的光吸收介导的。过氧化氢酶的直接失活和叶绿体介导的光失活都不受D2O或超氧化物歧化酶的影响，但甲酸盐对其有明显的抑制作用。在分离的过氧化体中，只有在没有光合作用的情况下才会发生过氧化氢酶的大量光失活，而在光合作用的单独叶绿体中则不会发生。当不同植物(黑麦、豌豆、向日葵、黄瓜、玉米)的叶片切段在翻译抑制剂放线菌酮或2-(4-methyl-2，6-dinitroanilino)-N-methylpropionamide，存在下用高强度的光照射时，体内的过氧化氢酶也观察到大量和选择性的光灭活，而在3-(3，4-dichlorophenyl)-1，1-dimethylurea-treated或未处理的对照切段中过氧化氢酶的活性受到很小的影响或不受影响。叶片中过氧化氢酶失活的程度与光强有关，红光下也有此现象。这些结果表明，在高光强下，叶片中普遍存在过氧化氢酶的光灭活现象，但在正常生理条件下，这种失活现象并不明显，因为它被新的合成所补偿。过氧化氢酶的表观光失活必须被认为是叶片光损伤的早期迹象，可以想见，它可以促进其进展。
Purified catalase from bovine liver and catalase of isolated intact peroxisomes from rye leaves were inactivated in vitro by irradiation with visible light. During photoinactivation the protein moiety of pure catalase was not cleaved; however, the electrophoretic mobility of the native enzyme was decreased, and a major portion of enzyme-bound heme was dissociated. In a suspension of isolated chloroplasts photoinactivation of pure or peroxisomal catalase was mediated by light absorption in the chloroplasts. Both the direct and the chloroplast-mediated photoinactivation of catalase were affected little by the presence of D2O or superoxide dismutase but were greatly retarded by formate. In isolated peroxisomes substantial photoinactivation of catalase occurred only in the presence of nonphotosynthesizing but not in the presence of photosynthesizing isolated chloroplasts. Substantial and selective photoinactivation of catalase was also observed in vivo when leaf sections from various plant species (rye, pea, sunflower, cucumber, maize) were irradiated with light of high intensity in the presence of the translation inhibitors cycloheximide or 2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide, while catalase activity was much less or not affected in 3-(3,4-dichlorophenyl)-1,1-dimethylurea-treated or untreated control sections. The extent of photoinactivation of catalase in leaves depended on light intensity and also occurred in red light. The results suggest that photoinactivation of catalase generally occurs in leaves under high light intensity, though it is not apparent under normal physiological conditions because it is compensated for by new synthesis. Apparent photoinactivation of catalase has to be regarded as an early indication of photodamage in leaves and conceivably enhances its progress.