What are the meanings of calcium in physiology?
The 'High-energy bond' 'myth'

The myth of the 'high-energy phosphate bond'

"It is frequently, and misleading, supposed that the phosphate anhydride bonds of ATP are 'high-energy' bonds which are capable of storing energy and driving reactions in otherwise unfavourable directions. However, it should be clear ... that it is the extent to which the observed mass-action ratio is displaced from equilibrium which defines the capacity of the reactants to do work, rather than any attribute of a single component. A hypothetical cell could utilize any reaction to transduce energy from the mitochondrion. For example, if the glucose-6-phosphatase reaction were maintained ten orders of magnitude away from equilibrium, then glucose-6-phosphate would be just as capable of doing work in the cell as is ATP. Conversely, the Pacific Ocean could be filled with an equilibrium mixture of ATP, ADP and Pi, but the ATP would have no capacity to work." (Nicholls & Ferguson, 1992, p.42)

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Created 30/5/99