摘要
用蔗糖密度梯度离心法从对照和盐处理的盐生车前根中分离出液泡膜，并对其ＡＴＰａｓｅ某些特性进行了比较研究。蔗糖连续密度梯度离心后，ＮＯ敏感的ＡＴＰａｓｅ活性主要分布在２２％－３５％蔗糖浓度之间，用不连续密度梯度离心法从２２％－３５％界面收集到的膜主要源于液泡膜。因为，这种膜ＡＴＰａｓｅ活性受到Ｃｌ￣－的促进和ＮＯ的强烈抑制，而叠氮化钠和正钒酸钠只抑制酶活性的１０％左右，最适ｐＨ８．０。对照和盐胁迫的液泡膜ＡＴＰａｓｅ活性均受Ｃｌ￣－和Ｂｒ￣－的激活，而ＮＯ、ＳＯ和Ｉ￣－均有抑制作用。对照和盐处理的液泡膜ＡＴＰａｓｅ均对ＡＴＰ亲和力最高，其次是ＧＴＰ，但后者对ＡＤＰ和ＵＴＰ也有部分水解作用，ＮａＣｌ胁迫后液泡膜ＡＴＰａｓｅ和ＰＰｉａｓｅ活性均明显增加，其Ｖｍａｘ也增加，但Ｋｍ没有变化，本文讨论了盐胁迫下液泡膜ＡＴＰａｓｅ变化的原因以及这些变化与植物耐盐性的关系。
Tonoplast vesicles were isolated from the roots of Plantago maritima L. with methods of su-crose density gradient and comparative studies were done on some properties of the tonoplast AT-Pase. After centrifugation of a linear sucrose density gradient , the nitrate-sensitive ATPase ac-tivity was mainly distriduted in a region of 22%-35%(w/w)sucrose. A membrane fractionwas collected from the interface of 22% 35%(w/w)sucrose by step sucrose gradient , theproperties of the membrane-bound ATPase activity prepared from both control and NaCl-stressed roots suggested that it was of tonoplast origin based on the following findings : optimalpH at 8.0 , stimulation by Cl￣-, strong inhibition by nitrate but only 10%inhibition by vanadateor azide. The effectiveness of anions of control and NaCl-stressed tonoplast ATPase activity wasstimulation : Cl￣-, Br￣- and inhibition : I￣-,NO ,SO . The substrate specificity of control and NaCl-stressed tonoplast ATPase was ATP>GTP , but the tonoplast ATPase of NaCl-stressed rootsposses a wide availability of nucleotides. Further , Km for MgATP was the same(0.5).Vmaxwas 0. 48 and 0. 73 mmol/L for control and NaCl-stressed roots,respectively,The activity ofATPase and PPiase on tonoplast from the roots of Platago maritima L. was increased obviouslyby NaCl stress. The reason from changes of the tonoplost ATPase and PPiase activities underNaCl-stress and the probable relationship between these changes and salt tolerance in plants wasdiscussed.
出处
《西北植物学报》
CAS
CSCD
北大核心
1995年第3期189-196,共8页
Acta Botanica Boreali-Occidentalia Sinica
基金
山东省自然科学基金
