STRUCTURE IDENTIFIABILITY IN METABOLIC PATHWAYS - PARAMETER-ESTIMATION IN MODELS BASED ON THE POWER-LAW FORMALISM

An important step in understanding a metabolic pathway is to identify its structure, in terms of the flow of material and information. In pu rsuing this goal, the available information for a given system is usua lly obtained from experiments in vitro and comes from different source s. Frequently, the final set of regulatory signals acting in the syste m in vivo is unclear, and some kind of test is needed on the intact sy stem. Besides defining an appropriate experimental approach, identific ation of the regulatory pattern needs a theoretical framework in which the different experimental measurements can be evaluated and a final picture can be agreed on. Mathematical approaches based on sensitivity coefficients provide a useful tool for addressing this problem. Withi n this framework, the appropriate parameters are related to both the s tructure of the reaction network and the signals that regulate the tar get system. Thus the identification of the regulatory structure can be related to the estimation of the appropriate set of parameters. In pu rsuing this goal, we will show the limitations of using steady-state m easurements and the usefulness of using dynamic data. We suggest a way to test the regulatory pattern in a given metabolic pathway by combin ing both kinds of data, and we show, by using a reference system, the potential of the method suggested.