Parameter identification of in vivo kinetic models: Limitations and challenges

Systems metabolic engineering of metabolic networks by genetic techniques requires kinetic equations for each enzyme present. In vitro studies of singular enzymes have limitations for predicting in vivo behavior, and in vivo experiments are constrained to retain viable cells. The estimation of kinetic parameters in vivo is a challenge due to the complexity of the internal cell environment. This concise review analyzes the limitations of in vitro and in vivo approaches, and shows that not all parameters can be determined and that multicollinearity exists. On the other hand, this review also shows that cell metabolism is adequately described with a smaller number of parameters and with approximative or reduced models. A major hurdle is the identification and quantification of allosteric effectors. Despite limitations, in vivo kinetic experiments are adequate in providing a quantitative description of the cell as a system. Details of enzyme kinetics in the living cell are necessary for understanding its behavior and designing microorganisms. The in vitro studies of singular enzymes are deficient in predicting the in vivo behavior, and in vivo experiments are constrained to retain viable cells. In this mini‐Review, the authors analyze the limitations and challenges of parameter identification of in vivo kinetic models in this. These limitations, however, are also opportunities as approximative models are all we need to explain the cell's behavior.