(667d) Unifying Flux Balance and Network-Based Pathway Analyses

Flux balance and network-based pathway analyses are theoretical tools aimed to find optimal steady state flux distributions in a metabolic network subject to additional constraints on the rates of the reaction steps. Although mathematically these methods are rigorous there are several physicochemical aspects, mainly interpretational, that are questionable and misleading. Most of these are due to the formal disconnection between the flux balance and network-based pathway analyses. The conventional flux balance and network-based pathway analyses are reformulated in terms of reaction routes (RRs), a theoretical framework that has been developed by Horiuti over 50 years ago. Not only the theory of RRs provides the most general and rigorous definition of a pathway but it also relates the steady state rates of the reaction steps with the rates along RRs or pathways. In this presentation we show how the simple relation between the steady state rates of the reaction steps and the rates along RRs (fluxes) established by Horiuti may be used to eliminate the FBA constraints. This new approach is in fact a way to unify the flux balance and pathway analyses.