Thermodynamics of the Hydrolysis Reactions of Adenosine 3', 5'-(Cyclic)phosphate(aq) and Phosphoenolpyruvate(aq); the Standard Molar Formation Properties of 3',5'-(Cyclic)Phosphate(aq) and Phosphoenolpyruvate(aq)

Published

November 1, 2003

Author(s)

Robert N. Goldberg, Yadu D. Tewari

Abstract

Molar calorimetric enthalpy changes DrHm(cal) have been measured for the biochemical reactions1 {ATP(aq) = cAMP(aq) + pyrophosphate(aq)} and {cAMP(aq) + H2O(l) = AMP(aq)}. The reactions were catalyzed, respectively, by adenosine 3',5'-(cyclic)phosphate and by alkaline phosphatase. The results were analyzed by using a chemical equilibrium model to obtain values of standard molar enthalpies of reaction DrH m for the respective reference reactions {cAMP-(aq) + H2O(l) = HAMP-(aq)}and {PEP3-(aq) + H2O(l) = pyruvate-(aq) + HPO42-(aq)}. Literature values of the apparent equilibrium constants K' for the reactions {ATP(aq) = cAMP(aq) + pyrophosphate(aq)}, {ATP(aq) + pyruvate(aq) = ADP(aq) + PEP(aq)}, and {ATP(aq) + pyruvate(aq) + phosphate(aq) = AMP(aq) + PEP(aq) + pyrophosphate(aq)} were also analyzed using the chemical equilibrium model. These calculations yielded values of the equilibrium constants K and standard molar Gibbs free energy changes DrG m for ionic reference reactions that correspond to the overall biochemical reactions. Combination of the standard molar reaction property values (K, DrH m, and DrG m) with the formation properties of the AMP, ADP, ATP, pyrophosphate, and pyruvate species led to values of the standard molar enthalpy DfH m and Gibbs free energy of formation DfG m and the standard partial molar entropy S m of the cAMP and PEP species. The thermochemical network is reasonably well reinforced. This fact lends some confidence to the accuracy of the calculated property values of the variety of species involved in the several reactions considered herein.

Citation

Journal of Chemical Thermodynamics

Volume

35

Issue

No. 11

Pub Type

Journals

Keywords

adenosine 3', 5'-cyclic)phosphate, Alkaline phosphatase, calorimetry, chemical thermodynamics, enthalpy, entropy, Gibbs free energy, phosphodiesterase 3', 5'-cyclic nucleoti, phosphoenolpyruvate

Citation

Goldberg, R. and Tewari, Y. (2003), Thermodynamics of the Hydrolysis Reactions of Adenosine 3', 5'-(Cyclic)phosphate(aq) and Phosphoenolpyruvate(aq); the Standard Molar Formation Properties of 3',5'-(Cyclic)Phosphate(aq) and Phosphoenolpyruvate(aq), Journal of Chemical Thermodynamics (Accessed April 25, 2024)