Coupling reaction
In living organisms: endergonic reaction will be drived by exergonic reaction
a molecule called ATP is responsible for driving most energy coupling in cells
Glu + NH3 + 3.4 kcal/mol Glu-NH2
ATP ADP + Pi + 7.3 kcal/mol
Glu + NH3 + ATP Glu-NH2 + ADP + Pi + 3.9