g., Ecocyc [17]) shows that signs for all genes were determined correctly. In this way the influence of transcription factor FruR on gene expression of the respective enzymes in glycolysis was determined; these values were further used in the steady

state and dynamic analysis of the glycolysis core model. 2.3. Validation with PtsG induced strains The model presented Inhibitors,research,lifescience,medical in previous studies [2,4] was extended as described in Material and Methods and AUY-922 price experimental data with the inducible PtsG strain were used. In this way, glucose is taken up by two systems: a non-PTS system (unspecific) and a PTS system (PtsG). With increasing amounts of IPTG, a shift from a non-PTS uptake situation to complete PTS uptake could be observed in the experimental data accompanied by increasing growth rates. Based on the data, several parameters could be determined that relate uptake by the the PTS and the non-PTS system with growth rate. To determine the kinetic parameters a sequential approach was chosen. First, a “rough” estimation of lumped parameters Inhibitors,research,lifescience,medical via nonlinear regression analysis was performed. To do so, reversibility of the glycolytic reaction rgly and the feedback of PEP to PfkA were neglected.

In this case, the degree of phosphorylation of EIIA could be described Inhibitors,research,lifescience,medical for growth on non-PTS sugars and PTS sugars in an analytical form. Moreover, as a result from our theoretical study [4], a value v = 1 was chosen. For non-PTS growth the degree of phosphorylation can be calculated as follows [4]: (8) and for PTS growth: (9) where parameters pi are lumped kinetic constants: (10) (11) (12) Considering now Inhibitors,research,lifescience,medical a simultaneous growth with both uptake systems, the uptake rate can be written as a sum: (13) and, consequently, depending on the fraction from the overall uptake rate,

the degree of phosphorylation Inhibitors,research,lifescience,medical will adjust accordingly. Given experimental data for non-PTS growth and PTS growth (data from [2]), and mixed growth (growth rates, degree of phosphorylation of EIIA for seven experiments 1–7, see Material and Methods) parameters pj as well as the fraction fj (μj) with j = 1,7 of Etomidate uptake via the non-PTS system could be estimated. Fraction fj (μj) is defined as: (14) In summary, 10 parameters are estimated based on 52 data points. Results of the fit are shown in Figure 4. Table 3 summarizes the results. Figure 4 Degree of phosphorylation of EIIA (EIIAP / EIIA0) versus growth rate. All data are taken from [2] (for the non-PTS data see Figure 3 left and Figure 7 left therein; for PTS data see Figure 3 right and Figure 7 right). Left (plot A): fit of the experimental … Table 3 Fraction fj of uptake via the non-PTS system after non-linear regression. As can be seen for experiment 1, it is estimated that glucose is completely taken up via the non-PTS uptake system; in experiment 6 a complete uptake via the PTS system through PtsG is calculated.