Equivalence of metabolite fragments and flow analysis of isotopomer distributions for flux estimation

The most accurate estimates of the activity of metabolic pathways are obtained by conducting isotopomer tracer experiments. The success of this method, however, is intimately dependent on the quality and amount of data on isotopomer distributions of intermediate metabolites. In this paper we present a novel method for discovering sets of metabolite fragments that always have identical isotopomer distributions, regardless of the velocities of the reactions in the metabolic network. We outline several applications of this equivalence concept, including improved propagation of measurements, experiment planning and consistency checking of metabolic network. Our computational experiments in measurement propagation indicate that the improvement via the use of this technique may be substantial.