ISSN:
1572-8927
Keywords:
Ammonia
;
apparent equilibrium constant
;
calorimetry
;
enthalpy
;
entropy
;
heat capacity
;
indole
;
pyruvic acid
;
thermodynamic properties
;
L-tryptophan
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 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 catalyzed 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) + NH 4 + (aq). At T=25°C and Im=O the results for this reaction are: Ko=(1.05±0.13)×10−4, ΔΓ G°=(22.71±0.33) kJ-mol−1, ΔΓ H°=(62.0±2.3) kJ-mol−1, and ΔΓ S°=(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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00973544
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