An Equilibrium and Calorimetric Investigation of the Hydrolysis of L-Tryptophan to (Indole + Pyruvate + Ammonia)

Article abstract of DOI:10.1007/BF00973544

Apparent equilibrium constants and calorimetric enthalpies of reaction have been measured for the reaction L-tryptophan(aq) + H2O(l) = indole(aq) + pyruvate(aq) + ammonia(aq) which is cataluzed by L-tryptophanase.High-pressure liquid-chromatography and microcalorimetery were used to perform these measurements.The equilibrium measurements were performed as a function of pH, temperature, and ionic strength.The results have been interpreted with a chemical equilibrium model to obtain thermodynamic quantities for the reference reaction: L-tryptophan(aq) + H2O(l)= indole(aq) + pyruvate^-(aq) + NH4⁺(aq).At T=25 deg C and I_m=0 the results for this reaction are: K⁰=(1.05+/-0.13)x10E-4, Δ_rG⁰=(22.71+/-0.33) kJ-mol^-1, Δ_rH⁰=(62.0+/-2.3) kJ-mol^-1, and Δ_rS⁰=(132+/-8) J-K^-1-mol^-1.These results have been used together with thermodynamic results from the literature to calculate standard Gibbs energies of formation, standard enthalpies of formation, standard molar entropies, standard molar heat capacities, and standard transformed formation properties for the substances participating in this reaction.