Thermodynamics of Reactions Catalyzed by Branched-Chain-Amino-Acid Transaminase

Published

October 1, 2000

Author(s)

Yadu D. Tewari, Robert N. Goldberg, J D. Rozzell

Abstract

Apparent equilibrium constants and calorimetric enthalpies of reaction have been measured for reactions catalyzed by branched-chain-amino-acid transaminase. The following biochemical reactions have been studied at the temperature 298.15 K and in the pH range (7.15 to 7.24): L-valine(aq) + 2-oxoglutarate(aq) = 2-oxoisovalerate(aq) + L-glutamate(aq); L-leucine(aq) + 2-oxoglutarate(aq) = 2-oxoisocaproate(aq) + L-glutamate(aq); and L-tert-leucine(aq) + 2-oxoglutarate(aq) = 3,3-dimethyl-2-oxobutanoate(aq) + L-glutamate(aq). The results have been used to calculate equilibrium constants and standard molar enthalpy,δ_rHo/m entropy, δ_rSo/m and Gibbs free energy δ_rGo/m changes for reference reactions involving specific species. Apparent equilibrium constants and standard transformed Gibbs energy changes for these reactions under physiological conditions have also been calculated. The use of these results for optimization of product yields of the branched-chain amino acids is discussed.

Citation

Journal of Chemical Thermodynamics

Volume

32

Issue

No. 10

Pub Type

Journals

Keywords

2-oxoglutarate, 3, 3-dimethyl-2-oxobutanoate, apparent equilibrium constant, branched-chain-amino-acid transaminase, enthalpy, entropy, Gibbs energy, L-glutamate, L-leucine

Citation

Tewari, Y. , Goldberg, R. and Rozzell, J. (2000), Thermodynamics of Reactions Catalyzed by Branched-Chain-Amino-Acid Transaminase, Journal of Chemical Thermodynamics (Accessed May 24, 2025)