Historical Perspective on Metabolic Energy and the Thermodynamics of Phosphate Compounds

1a Historical Perspective on Metabolic Energy and the Thermodynamics of Phosphate Compounds 

We have seen instances in the various biochemical examples that we have cited of a close coupling between an exergonic and an endergonic process. The need for such couplings to account for the observed appearances of the products of endergonic processes (for example, the synthesis of complex biological molecules from simple ones) was recognized for some time before the details 

The middle position that the ATP/ADP couple occupies in the potential ranking explains why it is so useful in cellular metabolism. There are numerous compounds lower on the potential scale to which the transfer of Pj represents a spontaneous process, and yet there are also a few cellular compounds with higher potentials that can in turn phosphorylate ADP to regenerate ATP. 

Hugh Huffman left Cal Tech during the Second World War and was an important scientist at a national laboratory set up to provide technical information to support the war effort. He left a legacy of high precision experimental techniques that yielded high-quality thermodynamic data on a wide variety of substances, including simple biological molecules. 

As part of this effort, Lipmann introduced the squiggle notation, P and used the terms bond energy and high-energy bonds to represent the amount of potential energy that could be stored in these bonds. In his book, Wanderings of a Biochemist, he says, 

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