Question

Shown is acetyl phosphate. Say a new enzyme uses acetyl phosphate to phosphorylate ADP to make ATP (acetyl phosphate + ADP —> acetate + ATP). What is the standard free energy change of this reaction?

CH3 Table 13-2 Standard Free Energies of Phosphate Hydrolysis of Some Compounds of Biological Interest AGo (kJ mol 1) 61.9 -49.4 45.6 43.1 -43.1 30.5 -20.9 19.2 13.8 13.8 -9.2 Compound Phosphoenolpyruvate 1,3-Bisphosphoglycerate ATP AMP + PP,) Acetyl phosphate Phosphocreatine ATP ㈠ ADP + Pi) Glucose-1-phosphate Fructose-6-phosphate Glucose-6-phosphate Glycerol-3-phosphate Source: Mostly from Jencks, W.P., in Fasman. G.D (Ed.), Handbook of Biochemistry and Molecular Biology (3rd ed.). Physical and Chemical Data, Vol. I, pp. 296-304, CRC Press (1976).

Answer 1

From the given chart we come to know the standard free energy for acetyl phosphate=43.1

standard free energy for ATP=45.6

Standard free energy change for the reaction=Gp-Gr(p-product,r-reactant) G=free energy of a molecule

                                                               =45.6-43.1

                                                                 =2.5 kj/mol