high-energy phosphate bond

A phosphate linkage with a negative standard free energy of hydrolysis, i.e. one that hydrolyses spontaneously, releasing energy. The last two phosphate bonds of ATP are examples.
Phosphate-bond energy is the major method of transfer of chemical energy from one enzymic reaction to another. For example, the high-energy phosphate bond of phosphoenolpyruvate can be broken to supply energy for the formation of ATP from ADP and phosphate. The ATP bond energy may then be used to drive an energy-requiring reaction, such as the formation of glutamine from glutamic acid.