摘要
经ＰＥＧ－１０００处理的高粱根，用不连续蔗糖密度梯度制备获得反转密闭的纯化质膜囊泡，显示一种特殊的ＡＴＰ酶活力，它不同于Ｈ＋－ＡＴＰ酶，其最适ＰＨ为７．５，具有高ＡＴＰ亲和力和较低的Ｋ＋转运能力。环己酰亚胺和钒酸钠能抑制其活力，表明它是新合成的Ｐ－型ＡＴＰ酶。
Sealed inside-out plasma membrane vesicles prepared by step sucrosegradient from sorghum (Sorghum L. Jinza No. 5 ) roots were used tostudy ATPase activity and K+ transportacross the membrane. In the absence ofMg2+, PM ATPase showed a PH optimum of 7. 5 under PEG-1000 stress. Itwas unlike plant PM H+-ATPase whichneed Mg2+ and had an optimum PH value of 6. 5 (Figs. 1, 2). Further researchproved that the ATPase had a highaffinity for ATP and a low K+ transport rate which was not related to H+transport(Figs. 3, 5 ). The inhibition ofits activity by cycloheximide and vanadate showed that it was a P--type ATPase synthesized de novo under osmoticstress(Fig. 4 ). Basing on these observations we conclude that the ATPase is aprimary ion-motive K+-ATPase induced by osmotic stress.
基金
国家自然科学基金
关键词
高梁
根
质膜囊泡
渗透胁迫
腺苷三磷酸酶
钾
sorghum root, plasma membrane vesicles,K￣+-ATPase, osmotic stress
