Hill T L, Eisenberg E
Q Rev Biophys. 1981 Nov;14(4):463-511. doi: 10.1017/s0033583500002468.
Free energy transfer from one small molecule (ligand, substrate, etc.) to another can in general be comprehended only in terms of complete kinetic cycles, not in terms of an individual transition in the cycle, or of a single 'energized' state in the cycle, or of binding strengths of the small molecules on the enzyme, or of their standard chemical potentials when bound. The reason these latter approaches fail is that the enzyme molecule is as much a specific participant in the step by step proceedings as are the small molecules; small molecule free energies cannot be separated from enzyme contributions or, in general, from each other except at the complete cycle level. It is possible to follow the 'flow' of the total free energy of enzyme + small molecules among various subdivisions or categories, as the system proceeds through the states of the transducing cycle. These categories can be understood in molecular terms but several of them involve the enzyme in a way that is inseparable from the small molecules. Hence this procedure also, does not allow localization within the cycle of the supposed point of transfer of free energy from one small molecule to another.
一般来说，一个小分子（配体、底物等）向另一个小分子的自由能转移，只能从完整的动力学循环角度来理解，而不能从循环中的单个转变、或循环中的单个“激发”态、或小分子与酶的结合强度、或它们结合时的标准化学势来理解。后几种方法失败的原因是，酶分子在逐步过程中与小分子一样，都是特定的参与者；小分子的自由能无法与酶的贡献分开，一般来说，除了在完整循环水平上，小分子之间的自由能也无法相互分开。当系统通过转导循环的各个状态时，可以追踪酶 + 小分子的总自由能在各个细分部分或类别之间的“流动”。这些类别可以从分子角度来理解，但其中几个类别涉及酶的方式与小分子不可分割。因此，这个过程也不允许在循环中定位从一个小分子到另一个小分子的自由能转移的假定点。
