A MINIMAL INPUT-OUTPUT CONFIGURATION FOR A PRIORI IDENTIFIABILITY OF A COMPARTMENTAL MODEL OF LEUCINE METABOLISM

To develop a model describing the structure and function of a metaboli c system using data from an input-output experiment, it is useful to d esign a pilot tracer study first which contains a predicted maximal am ount of information. Having postulated a physiologically reasonable mo del structure from the pilot data, two questions arise. First, are the model parameters a priori uniquely identifiable? That is, assuming an error-free model Structure and data, can the parameters be uniquely i dentified from the information content of the pilot experiment? Second , if the model parameters are uniquely identifiable, is the pilot expe riment a minimal one? That is, is the pilot experiment necessary and s ufficient, in the sense of information content, among feasible experim ents to guarantee a priori unique identifiability? The purpose of this paper is to determine a minimal input-output configuration for the a priori unique identifiability of a compartmental model describing the metabolism of leucine, Bn essential amino acid. The original pilot tra cer experiment was a two-stage experiment consisting first of a two in put-five output experiment followed by a single input-single output ex periment. Here we show to guarantee a priori unique identifiability of the leucine model that the single input-single output experiment is n ot necessary, and that two of the outputs of the multiinput-multi-outp ut experiment are not required.