In silico analysis of lactic acid secretion metabolism through the top-down approach: Effect of grouping in enzyme kinetics

A top-down approach is known to be a useful and effective technique for the design and analysis of metabolic systems. In this study, we have constructed a grouped metabolic network forLactococcus lactis under aerobic conditions using grouped enzyme kinetics. To test the usefulness of grouping work, a non-grouped system and grouped systems were compared quantitatively with each other. Here, grouped systems were designed as two groups according to the extent of grouping. The overall simulated flux values in grouped and non-grouped models had pretty similar distribution trends, but the details on flux ratio at the pyruvate branch point showed a little difference. This result indicates that our grouping technique can be used as a good model for complicated metabolic networks, however, for detailed analysis of metabolic network, a more robust mechanism should be considered. In addition to the data for the pyruvate branch point analysis, some major flux control coefficients were obtained in this research.