Meister M, Lowe G, Berg H C
Cell. 1987 Jun 5;49(5):643-50. doi: 10.1016/0092-8674(87)90540-x.
Bacterial flagella are driven by a rotary motor that utilizes the free energy stored in the electrochemical proton gradient across the cytoplasmic membrane to do mechanical work. The flux of protons coupled to motor rotation was measured in Streptococcus and found to be directly proportional to motor speed. This supports the hypothesis that the movement of protons through the motor is tightly coupled to the rotation of its flagellar filament. Under this assumption the efficiency of energy conversion is close to unity at the low speeds encountered in tethered cells but only a few percent at the high speeds encountered in swimming cells. This difference appears to be due to dissipation by processes internal to the motor. The efficiency at high speeds exhibits a steep temperature dependence and a sizable deuterium solvent isotope effect.
细菌鞭毛由一个旋转马达驱动，该马达利用跨细胞质膜的电化学质子梯度中储存的自由能来做机械功。在链球菌中测量了与马达旋转耦合的质子通量，发现其与马达速度成正比。这支持了这样一种假设，即质子通过马达的运动与其鞭毛丝的旋转紧密耦合。在这个假设下，在拴系细胞中遇到的低速时，能量转换效率接近100%，但在游动细胞中遇到的高速时，效率仅为百分之几。这种差异似乎是由于马达内部过程的耗散所致。高速时的效率表现出强烈的温度依赖性和可观的氘溶剂同位素效应。
