Electrogenic K+ transport by the Kdp-ATPase of Escherichia coli.
Electrogenic K+ transport by the Kdp-ATPase of Escherichia coli.
复制标题
大肠杆菌 Kdp-ATP 酶产生的电 K 转运。
作者：
K. Fendler;S. Dröse;K. Altendorf;E. Bamberg
通过蛋白脂质体在平面脂质膜上的吸附，测定了大肠杆菌kdp - atp酶的电荷易位。将纯化的kdp - atp酶重组到大肠杆菌脂质体中制备蛋白脂质体。该蛋白被ATP的受保护衍生物（笼化ATP）光解产生的ATP浓度跳跃所激活。电荷移位的时间分辨率为15-40 ms。静止电流证明了酶的连续泵送活性。用电位敏感染料DiSC3(5)进行的对照测量显示，在ATP激活后，蛋白脂质体内部出现负电位。测量到的电信号以及染料测量与正电荷到蛋白质细胞内表面的传输相对应。当K+在蛋白脂质体内（K0.5约50微米）时，电信号增强，并被钒酸盐抑制。这些实验证明了kdp - atp酶在纯化重组体系中的电性。
Charge translocation by the Kdp-ATPase of Escherichia coli was measured by adsorption of proteoliposomes to a planar lipid membrane. The proteoliposomes were prepared by reconstitution of purified Kdp-ATPase into liposomes prepared from E. coli lipids. The protein was activated by a ATP concentration jump produced by photolysis of a protected derivative of ATP, caged ATP. Charge translocation was measured with a time resolution of 15-40 ms. Stationary currents demonstrated the continuous pumping activity of the enzyme. Control measurements with the potential-sensitive dye DiSC3(5) showed a negative potential inside the proteoliposomes after activation with ATP. The measured electrical signals as well as the dye measurements correspond to the transport of positive charge to the intracellular face of the protein. The electrical signal was increased when K+ was inside the proteoliposomes (K0.5 approximately 50 microM) and was inhibited by vanadate. These experiments demonstrate the electrogeneity of the Kdp-ATPase in a purified reconstituted system.