The elongation phase of protein synthesis is a cyclic, steady-state process. It follows that its directionality is determined by the thermodynamics of the accompanying chemical reactions, which strongly favor elongation. Its irreversibility is guaranteed by its coupling to those reactions, rather being a consequence of any of the conformational changes that occur as it unfolds. It also follows that, in general, the rate of elongation is not proportional to the forward rate constants of any of its steps, including its final, mechano-chemical step, translocation. Instead, the reciprocal of the rate of elongation should be linearly related to the reciprocal of those rate constants. When the results of experiments done a decade ago to measure the effect that forces opposing translocation have on the rate of elongation are reinterpreted in light of these findings, it becomes clear that translocation was rate limiting under conditions in which those experiments were done, and that it is likely to be a Brownian ratchet process, as was concluded earlier.

中文翻译：

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关于延长核糖体对反对易位的力的反应


蛋白质合成的延伸阶段是一个循环的稳态过程。由此可见，它的方向性是由伴随的化学反应的热力学决定的，这强烈有利于伸长。它的不可逆性是通过它与这些反应的耦合来保证的，而不是它展开时发生的任何构象变化的结果。还可以得出结论，一般来说，伸长速率与其任何步骤的正向速率常数不成正比，包括其最终的机械化学步骤易位。相反，伸长率的倒数应与这些速率常数的倒数线性相关。当根据这些发现重新解释十年前为测量反向易位对伸长率的影响而进行的实验结果时，很明显易位在进行这些实验的条件下是速率限制的，并且正如之前所得出的结论，这很可能是一个布朗棘轮过程。