A Thermodynamic Study of the Conversion of Chorismate to Isochorismate

Published

August 1, 2000

Author(s)

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

Abstract

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 chorismate^2-(aq) = isochorismate^2-(aq), the equilibrium constant K = (0.84 0.04) and the standard molar enthalpy of reaction δ_rH _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 δ_fG'_m = 0.49 kJ mol^-1 for the overall biochemical reaction.

Citation

Journal of Chemical Thermodynamics

Volume

32

Issue

8

Pub Type

Journals

Keywords

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

Citation

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 February 11, 2026)