Thermodynamics of the Hydrolysis Reactions of ±-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4 nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

Published

May 1, 2009

Author(s)

Robert N. Goldberg, Brian E. Lang, Catherine T. Lo, David J. Ross, Yadu D. Tewari

Abstract

Microcalorimetry, high-performance liquid chromatography, and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: α-D-galactose 1 phosphate(aq) + H2O(l) = D-galactose(aq) + orthophosphate(aq) (1), sn-glycerol 3-phosphate(aq) + H2O(l) = glycerol(aq) + orthophosphate(aq) (2), 4-nitrophenyl phosphate(aq) + H2O(l) = 4-nitrophenol(aq) + orthophosphate(aq) (3), phosphocreatine(aq) + H2O(l) = creatine(aq) + orthophosphate(aq) (4), and 3-phospho-D-glycerate(aq) + H2O(l) = D-glycerate(aq) + orthophosphate(aq) (5). Calorimetrically determined enthalpies of reaction ΔrH(cal) were measured for reactions (1) to (5) and the apparent equilibrium constant K was measured for reaction (2). The necessary values of pK and standard enthalpies of reaction ΔrHo for the H+ and Mg2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate thermodynamic property values (equilibrium constants K and standard enthalpies of reaction) for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. These results were compared with previously reported results from the literature and also correlated with structural features. The results obtained in this study can be used together with the chemical equilibrium model to calculate values of K , the standard apparent Gibbs energy change ΔrG o, the standard apparent enthalpy change ΔrH o, changes in binding of the proton ΔrN(H+), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, and ionic strength.

Citation

Journal of Chemical Thermodynamics

Volume

41

Issue

5

Pub Type

Journals

Keywords

alkaline phosphatase, apparent equilibrium constants, ±-D-galactose 1-phosphate, sn-glycerol 3 phosphate, 4 nitrophenyl phosphate, phosphocreatine, 3-phospho-D-glycerate, calorimetry, standard Gibbs energy and enthalpy.

Citation

Goldberg, R. , Lang, B. , Lo, C. , Ross, D. and Tewari, Y. (2009), Thermodynamics of the Hydrolysis Reactions of ±-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4 nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate, Journal of Chemical Thermodynamics (Accessed December 26, 2024)