coupled reaction

In other words, it is measuring a secondary, coupled reaction.

The G value of the coupled reaction is -1.8 kcal/mole, indicating that the reaction will occur spontaneously.

Overall, nonspontaneous reactions coupled to the dephosphorylation of ATP are spontaneous, due to the negative free energy change of the coupled reaction.

In other words, phosphocreatine acts as high-energy reserve in a coupled reaction; the energy given off from donating the phosphate group is used to regenerate the other compound - in this case, ATP.

The carboxylation reaction will only proceed if the carboxylase enzyme is able to oxidize vitamin K hydroquinone to vitamin K epoxide at the same time; the carboxylation and epoxidation reactions are said to be coupled reactions.

Thiol S-nitrosylation and NO transfer reactions (transnitrosation reactions) are involved in virtually all classes of cell signaling, ranging from regulation of ion channels and G-protein coupled reactions to receptor stimulation and activation of nuclear regulatory protein.