Phosphate group transfer potential

The free energies of hydrolysis (phosphate group transfer potential) of the compounds in the classes we have been discussing are important to their roles as phosphate donors and acceptors, and as carriers of chemical energy in metabolism. Table III-2 lists some of these free energies under standard conditions (pH 7, 25°C, 1 M reactants and products). A... 

The tendency of ATP to undergo hydrolysis, also referred to as its phosphate group transfer potential, is not unique. A variety of biomolecules can transfer phosphate groups to other compounds. Table 4.1 lists several important examples. 

Which of the following compounds would have the higher phosphate group transfer potential Explain your answer ... 

What is the difference between an enol-phosphate ester and a normal phosphate ester that gives PEP such a high phosphate group transfer potential ... 

Phosphoenolpyruvate has the greatest phosphate group transfer potential. On hydrolysis, the enol which has a resonance restricted... 

For this reaction, AjG = 0 because the phosphate group transfer potentials for GTP and ATP are essentially identical. Overall, we write the oxidation of glucose as a result of glycolysis and the citric acid cycle as... 

In contrast to the ion exchange theory, much evidence indicates that cells have an active ion pump that removes Na+ from cells and introduces K+. For example, the cytoplasm of the giant axons of nerves of squid can be squeezed out and replaced by ionic solutions. Erythrocyte ghosts can be allowed to reseal with various materials inside. Ion transport into or out of cells has been demonstrated with such preparations and also with intact cells of many types. Such transport is blocked by such inhibitors as cyanide ion, which prevents nearly all oxidative metabolism. However, the cyanide block can be relieved by introduction into the cells of ATP and other phosphate compounds of high group-transfer potential. 

The carboxyl group enters on the si face of PEP. However, there is another possibility.295 296 The carboxyl phosphate, while in the active site adjacent to the enolate anion, may eliminate phosphate, the enolate ion adding to the resulting C02 to form the final product. According to this mechanism the group transfer potential of the phosopho group in PEP is... 

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