Determining the free energy change of a reaction under physiological conditionsthat is, within a living organismrequires consideration of factors beyond standard conditions. These factors include the actual concentrations of reactants and products, temperature, pH, and ionic strength within the cellular environment. For instance, the concentration of magnesium ions (Mg) can significantly impact the free energy available from the hydrolysis of adenosine triphosphate (ATP).
Accurate assessment of free energy changes in vivo is crucial for understanding metabolic pathways and cellular processes. Knowing the true energetic driving force of reactions allows researchers to predict the directionality of reactions and identify potential control points in metabolic networks. This understanding is fundamental to fields such as drug discovery, where manipulating the energetics of specific enzymatic reactions can be a key therapeutic strategy. Historically, determining these values has been challenging due to the complexity of intracellular environments. However, advancements in experimental techniques and computational methods are now providing more precise measurements and estimations of free energy changes within cells.
