Rapid-Equilibrium Enzyme Kinetics.

• Autores: Robert A. Alberty
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 85, Nº 8, 2008, págs. 1136-1141
• Idioma: inglés
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• Resumen

  • Rapid-equilibrium rate equations for enzyme-catalyzed reactions are especially useful because if experimental data can be fit by these simpler rate equations, the Michaelis constants can be interpreted as equilibrium constants. However, for some reactions it is necessary to use the more complicated steady-state rate equations. Thermodynamics is used in rapid-equilibrium derivations to calculate the equilibrium concentrations of reactants up to the rate-determining reaction, and that means that the reactions in the mechanism have to be independent. This is quite different from steady-state treatments of mechanisms where reactions do not have to be independent. The innovation in this article is the use of half-reactions to construct complete rapid-equilibrium rate equations. Five half-reactions are described. Any forward half-reaction can be combined with any reverse half-reaction. Rapid-equilibrium rate equations are given for fifteen mechanisms of enzyme-catalyzed reactions, but more rate equations can be constructed from these five half-reactions.