AN INTEGRATED METABOLIC PATHWAY ANALYSIS BASED ON METABOLIC SIGNAL FLOW DIAGRAM AND CELLULAR ENERGETICS FOR SACCHAROMYCES-CEREVISIAE

Noting that a metabolic signal flow diagram-based modelling approach d eveloped by Endo and Inoue (Endo and Inoue, 1976) is restricted to a l inear system applicable over the range of linearity of interest, we at tempted to overcome such a restriction, and developed an integrated mo delling approach by incorporating an energetic model into MSFD. The pr oposed approach was applied to continuous cultivation of Saccharomyces cerevisiae. The problem was formulated in terms of a how network that has as its objective maximal ATP synthesis. The metabolic conversion coefficients C-ij in the metabolic signal flow diagram can be expresse d as a function of z, the fraction of the total carbon flux into the E mbden-Meyerhof-Parnas pathway. The resulting model equations were used for analysis of the directions of carbon fluxes and the degree of act ivation of a particular pathway or reaction loop in S. cerevisiae cult ivation, in which the physiological state and the changes in fluxes of the main metabolic pathways in the viable cells can he distinguished in terms of the signs of the metabolic coefficients,