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A Thermodynamic Study of the Conversion of Chorismate to Isochorismate



Yadu D. Tewari, A M. Davis, Prasad T. Reddy, Robert N. Goldberg


Microcalorimetry and high performance liquid chromatography were used to conduct a thermodynamic investigation of the biochemical reaction chorismate(aq) = isochorismate(aq). this reaction occurs at the branch point of the chorismate metabolic pathway that leads to the synthesis of enterobaction. Isochorismate synthase, the enzyme that catalyzes this reaction, was prepared for this study by using molecular biology techniques. The equilibrium and calorimeteric measurements were performed at the temperature T = 298.15 K and at the respective pHs 7.34 and 6.93. For the chemical reference reaction chorismate2-(aq) = isochorismate2-(aq), the equilibrium constant K = (0.84 0.04) and the standard molar enthalpy of reaction δrH m = (0.81 ).27) kJ mol-1 at T = 298.15 K and ionic strength I = 0. Under approximately physiological conditions, the apparent equilibrium constant K' = 0.83 and the standard transformed Gibbs energy change δfG'm = 0.49 kJ mol-1 for the overall biochemical reaction.
Journal of Chemical Thermodynamics


apparent equilibrium constant, chorismate, entropy, Gibbs free energy, isochorismate synthase, transformed thermodynamic quantities


Tewari, Y. , Davis, A. , Reddy, P. and Goldberg, R. (2000), A Thermodynamic Study of the Conversion of Chorismate to Isochorismate, Journal of Chemical Thermodynamics (Accessed May 26, 2024)


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Created August 1, 2000, Updated February 17, 2017