\frac{dx_{1}}{dt} = \left(-\left(k_{1} + k_{2}\right)\right) \cdot x_{1} + k_{7} \cdot x_{2} + k_{3} \cdot k_{12} / \left(k_{13} \cdot 400000\right) \cdot \frac{1}{1000} \cdot x_{3}\\
\frac{dx_{2}}{dt} = k_{1} \cdot x_{1} - k_{7} \cdot x_{2}\\
\frac{dx_{3}}{dt} = k_{2} \cdot k_{12} / \left(k_{13} \cdot 400000\right) \cdot \frac{1}{1000} \cdot x_{1} - \left(k_{3} + k_{4}\right) \cdot x_{3} + k_{5} \cdot x_{4} - k_{8} \cdot \left(k_{9} - x_{5}\right) \cdot x_{3} + k_{14} / k_{13} \cdot k_{6} \cdot x_{5}\\
\frac{dx_{4}}{dt} = k_{4} \cdot x_{3} - k_{5} \cdot x_{4}\\
\frac{dx_{5}}{dt} = k_{8} \cdot k_{14} / k_{13} \cdot \left(k_{9} - x_{5}\right) \cdot x_{3} - k_{6} \cdot x_{5}