Samuel A D, Berg H C
Rowland Institute for Science, Cambridge, MA 02142, USA.
Proc Natl Acad Sci U S A. 1995 Apr 11;92(8):3502-6. doi: 10.1073/pnas.92.8.3502.
We measured the dependence of the variance in the rotation rate of tethered cells of Escherichia coli on the mean rotation rate over a regime in which the motor generates constant torque. This dependence was compared with that of broken motors. In either case, motor torque was augmented with externally applied torque. We show that, in contrast to broken motors, functioning motors in this regime do not freely rotationally diffuse and that the variance measurements are consistent with the predicted values of a stepping mechanism with exponentially distributed waiting times (a Poisson stepper) that steps approximately 400 times per revolution.
我们测量了在大肠杆菌系留细胞旋转速率的方差对平均旋转速率的依赖性，该过程处于电机产生恒定扭矩的状态。将这种依赖性与损坏的电机的依赖性进行了比较。在任何一种情况下，电机扭矩都通过外部施加的扭矩来增强。我们表明，与损坏的电机不同，处于这种状态下的正常运行电机不会自由地进行旋转扩散，并且方差测量结果与具有指数分布等待时间的步进机制（泊松步进器）的预测值一致，该步进器每转大约步进400次。
