The use of the thermodynamic formalism in the investigation of biochemical reactions constitutes one of the key analysis in bioenergetics, and the first step in such analysis is the selection of the adequate reference state. For biochemistry majors, thermodynamic analysis based on the chemical reference state is used in Physical Chemistry courses, while the biological and biochemical reference states are used in Biochemistry courses. As these definitions are introduced in different courses, it is difficult that students can understand the need to select a reference state as a first step in the energy analysis of a system. The lack of suitable examples in textbooks to illustrate the importance of the adequate selection of the reference state in a thermodynamic analysis, promoted the present analysis of the energetic role of pyrophosphate (PPi) in comparison with adenosine‐triphosphate in different ambient conditions, namely, the early PPi world (better described by the chemical reference state), the enclosed systems like the cells (better described by the biological reference state), and the actual thioester world (better described by the biochemical reference state). This example not only provides a new interesting point of view on the evolution of two biochemical fuels but also represents a biochemical example in which the use of different reference states can illustrate a single process from different points of views.

中文翻译：

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选择合适的热力学参考状态：以焦磷酸盐生物能学的演变为例

热力学形式主义在生化反应研究中的应用构成了生物能学的关键分析之一，这种分析的第一步是选择适当的参考状态。对于生物化学专业，物理化学课程使用基于化学参考状态的热力学分析，而生物化学课程使用生物和生化参考状态。由于这些定义是在不同的课程中介绍的，因此学生很难理解需要选择参考状态作为系统能量分析的第一步。The lack of suitable examples in textbooks to illustrate the importance of the adequate selection of the reference state in a thermodynamic analysis, 促进了目前对焦磷酸盐 (PPi) 与不同环境条件下的三磷酸腺苷的能量作用的分析，即早期 PPi 世界（由化学参考状态更好地描述），封闭系统如细胞（更好地描述为生物参考状态）和实际硫酯世界（由生化参考状态更好地描述）。这个例子不仅为两种生化燃料的演化提供了一个新的有趣的观点，而且代表了一个生化例子，在这个例子中，使用不同的参考状态可以从不同的角度说明一个过程。封闭系统，如细胞（由生物参考状态更好地描述）和实际硫酯世界（由生化参考状态更好地描述）。这个例子不仅为两种生化燃料的演化提供了一个新的有趣的观点，而且代表了一个生化例子，在这个例子中，使用不同的参考状态可以从不同的角度说明一个过程。封闭系统，如细胞（由生物参考状态更好地描述）和实际硫酯世界（由生化参考状态更好地描述）。这个例子不仅为两种生化燃料的演化提供了一个新的有趣的观点，而且代表了一个生化例子，在这个例子中，使用不同的参考状态可以从不同的角度说明一个过程。