蛋白质修饰剂、变性剂和活性氧对菠菜叶片光系统Ⅱ光失活的影响(英文)

EFFECTS OF PROTEIN MODIFIERS, DENATURANTS AND ACTIVE OXYGEN ON PHOTOSYSTEM Ⅱ PHOTOINACTIVATION OF SPINACH LEAVES

菠菜叶圆片以活性氧、蛋白质修饰剂和变性剂结合强光处理半小时，检测叶绿素荧光动力学并与单照强光的对照作比较。加人H2O2、·O2、OH·和O2等活性氧加剧了PSⅡ的光抑制作用，Fv／Fm，qp和PSⅡ降低，qn和1—qp相应上升。4种蛋白质修饰剂NBS、DEPC、BDE和pCMB的处理，使叶片的Ch1荧光参数发生了与活性氧作用相类似的变化，尤以精氨酸残基修饰剂BDE的影响较为显著。SDS明显地影响FV和qp但未改变qN值。Gu－HC1导致qp完全丧失，qN达最大值。低浓度的脲素和DMSO略为降低PSⅡ活性和增大qN。结果认为对叶绿体蛋白构象或结构的任何改变皆引起光下PSⅡ光失活作用的增强。

Leaf discs of spinach were exposed to high light in the presence of active oxygen,protein modifiers and denaturants, and chlorophyll fluorescence kinetics was detected and compared with high light treatment alone.The addition of H2O2, O2-, OH and 'O2 enhanced photoinhibition, showing the decrease of Fv/Fm, qp and PSⅡ, which were accompanied by the increase of qN and 1 -qp. Treatment of four protein modifiers, NBS, DEPC, BDE and pCMB, also exhibited the similar changes of fluorescence parameters. More evident change was caused by BDE, an Arg-modifier of protein. SDS affected significantly on Fm, Fv and qp, but didn't change qN. A complete lose of qp associated with maximum qN were induced by Gu-HCl. Urea and DMSO at low concentration reduced the PSⅡ activitv and increased qN in less extent. The results suggest that any change in conformation or structure of chloroplast protein all led to the enhancement of PSll photoinactivation.