In the process of biological metabolism phosphoric acid Phosphoric acid bond formed by dehydration, its phosphoric acid group hydrolysis Released free energy There are great differences. Some free energies vary from - 2000 to - 3000 cal, such as 3- Glycerol phosphate 、 gland nucleotide Etc; Others such as inorganpyrophosphate 、 Acetylphosphoric acid 、 creatine Phosphoric acid Phosphoenolpyruvate Isophosphate compound, per mole During molecular hydrolysis, the free energy changes from - 7000 to - 12000 cal. Based on these experimental results, biochemistry The latter type of phosphoric acid bond is called high-energy phosphoric acid bond, while compounds with high-energy phosphoric acid bond are called High-energy phosphoric acid compound ； On the other hand, the former is called Low-energy phosphate bond (with 5000cal as the boundary), molecules without high-energy phosphoric acid bond are called low-energy Phosphoric acid compounds. According to the bond type, high-energy phosphate bonds can be simply classified [1] 。
The oxygen phosphorus bond type (- O-P -) is composed of hydroxyl group (- OH ）And phosphoric acid dehydration synthesis Obtained Chemical bond 。 It mainly includes: 1. Acyl phosphate bond:
Usually carboxyl And phosphoric acid. Common examples are Acetylphosphoric acid 、 1,3-Diphosphoglycerate 、 Carbamoyl phosphate High energy phosphoric acid bond in, etc. It is formed by dehydration and condensation of phosphoric acid and hydroxyl group on another phosphoric acid molecule. Common examples are inorganpyrophosphate 、 ADP 、 ATP High energy phosphoric acid bond in, etc. 3. Enol phosphate bond:
For phosphoric acid and Enol The chemical bond obtained by dehydration and condensation of the compound of formula. Common examples are Phosphoenolpyruvate High energy phosphoric acid bond in, etc. The nitrogen phosphorus bond type (- N-P -) is composed of amino （-NH two ）The chemical bond obtained by dehydration and condensation with phosphoric acid. The common ones are Phosphocreatine 、 Arginine phosphate High energy phosphoric acid bond in, etc. High energy phosphate compounds in the body are often associated with energy storage/release. as ATP , as the "currency" of cell energy, it is produced by hydrolysis or group transfer Release energy 。 High energy phosphate bonds are often mistaken for high Bond energy 。 Actually, yes Polyatomic molecule , the bond energy is defined as "the energy absorbed by 1mol gaseous molecule completely dissociated into gaseous atoms is distributed to Structural In covalent bond Energy ". That is, bond energy can be simply understood as the energy to be absorbed when a bond breaks. chemical reaction Essentially, it is the fracture of old bonds and the generation of new bonds, generally Broken key As long as the total energy released by the generation of all new bonds is greater than the energy absorbed by the breaking of all old bonds, the overall reaction will release energy. For the energy release of high-energy phosphoric acid bond hydrolysis reaction, it is obvious that the breaking absorption energy of high-energy phosphoric acid bond is far less than the energy released by the formation of new "conventional" or "low-energy" chemical bonds, and the excess energy can be released. In fact, because of the above principle, Phosphoric acid groups connected by high-energy phosphoric acid bonds often spontaneously transfer to other groups (thus generating "conventional" chemical bonds) Chemical potential 。 [1] Therefore, "high energy" in the concept of high energy phosphoric acid bond refers to Spontaneous reaction Generating other compounds potential energy , rather than "bond energy". This is also easy to happen in biological phosphorylation Chemical essence 。 
