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High energy phosphate

High energy phosphate can mean one of a couple things:

High energy phosphate bonds are pyrophosphate bonds, acid anhydride linkages, formed by taking phosphoric acid derivatives and dehydrating them. As a consequence, the hydrolysis of these bonds is exothermic under physiological conditions, releasing energy.

Energetic of High Energy Phosphate Reactions
ReactionΔ G in Kilojoules/mole
ATP + H2O → ADP + Pi -36.8
ADP + H2O → AMP + Pi -36.0
ATP + H2O → AMP + PPi -40.6
PPi → 2 Pi -31.8
AMP + H2O → A + Pi -12.6

These reactions are generally not allowed to go uncontrolled in the human cell, but generally are coupled to other processes needing energy to drive them to completion. So, high energy phosphate reactions can

Often, high energy phosphate bonds are denoted by the character '~'. In this notation, ATP becomes A-P~P~P.

McGilvery, R. W. and Goldstein, G., Biochemistry - A Functional Approach, W. B. Saunders and Co, 1979, 345-351.