Free energy dissipation of the pyruvate kinase reaction has a minimum at cell metabolite concentrations

Abstract

The ratio of substrates and products (mass action ratio) for the reaction catalyzed by the enzyme pyruvate kinase is measured under the constraint of constant reaction rate for pyruvate kinase (EC 2.7.1.40) from brewers yeast and Escherichia coli. For both organisms, a maximum of the ratio is found at concentrations comparable to those obtained from cell metabolite measurements. This observation suggests an optimum principle for free energy transduction in the glycolytic reaction pathway, as a maximum of the mass action ratio corresponds to a minimum dissipation of free energy.