NaN_3对叶绿体Mg^（2＋）－ATPase的抑制作用再探  

Further Study on the Inhibitory Effect of Azide on Chloroplast Mg￣(2+)- ATPase

作　　者：魏家绵[1] 李朝晖 李德耀[1] 

机构地区：[1]中国科学院上海植物生理研究所

出　　处：《植物生理学报（0257-4829)》1994年第2期163-170,共8页Acta Phytophysiologica Sinica

基　　金：国家自然科学重点基金

摘　　要：ＮａＮ３能抑制新鲜菠菜叶片叶绿体经ＤＴＴ和光激活的Ｍｇ２＋－ＡＴＰａｓｅ活力。这种抑制属非竞争性抑制。ＮａＮ３还能降低新鲜菠菜叶片叶绿体的反映光合磷酸化高能态的毫秒延迟发光和减少反映类爱体膜质子吸收变化的叶绿体的９－氨基吖啶的荧光猝灭。菠菜叶片经低温贮存几天后其叶绿体的超微结构发生变化，ＮａＮ３对叶绿体的上述影响就消失或基本消失。本实验指出ＮａＮ３是新鲜叶片叶绿体Ｈ＋－ＡＴＰａｓｅ的一个强有力的抑制剂。其影响受叶绿体制剂的内源无机磷酸盐含量调节。Effect of azide on chloroplastMg2+--ATPase activity has been studiedfurther. The results showed that azidecould inhibit the Mg2+--ATPase activityof the chloroplasts isolated from freshspinach leaves after being activated byDTT and light. The degree of its inhibition always increased as azide concentration in dark reaction mixture rose(Fig. 1 ). However, the inhibitory effect of azide on the Mg2+--ATPase ofthe chloroplasts varied significantly inthe different chloroplast preparationsTable 1 ). In the kinetic study, it wasquite clear that the lines for control andazide--inhibited one in double reciprocalplots crossed at the abscissa. It showsthat there is a non--competitive relationship between azide and[ Mg2+.ATP ] in this reaction (Fig. 2 ). Whenazide inhibited the Mg2+--ATPase activity of the chloroplasts it also decreasedthe 9--aminoacridine fluorescencequenching and the millisecond delayedlight emission of the chloroplasts(Figs.3, 4 ). On the other hand, when spinachleaves were placed at low temperaturefor some days(e. g 4 ℃, four days ).The effects of azide on chloroplasts described above all vanished or were lesspronounced (Table 2).Azide inhibition of the Mg2+ ATPase activity of chloroplasts was also controlled by the endogenous inorganic phosphate content of chloroplasts. Azide inhibition can be enhanced bydecreasing the endogenous inorganicphosphate content of chloroplasts bywashing with a mixture of 0. 4 mol/Lsucrose, 0. o1 mol/L NaCl and 0. 02mol/L Tris-- HCl, PH 7. 4 for chloroplasts from either fresh or treatedspinach leaves(Table 3 ).The above results indicate thatazide is a potent inhibitor of chloroplastH+--ATP--ase of fresh leaves in hydrolyzing ATP. It can diminish the proton gradient across thylakoid membranes, and thereby inhibit the ATPaseactivity of chloroplasts activated byDry and light. When structural changeo f chloroplasts took place in spinachleaves after low temperature storage(Table 5), the azide action site on thecoupling factor of chloroplasts might behidden completely or to a larg

关 键 词：叶绿体 类囊体 镁 腺苷三磷酸酶 

分 类 号：Q732[生物学—分子生物学]