\frac{dx_{1}}{dt} = \left(1 \cdot k_{15} \cdot k_{1} \cdot x_{1} \cdot \left(1 - k_{2} / k_{12} \cdot x_{1}\right) + -1 \cdot k_{15} \cdot k_{3} \cdot x_{1} / \left(k_{4} \cdot k_{12} + x_{1}\right) \cdot x_{2}\right) / k_{15}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{15} \cdot \left(k_{5} \cdot x_{3} / \left(k_{6} \cdot x_{3}\right) \cdot x_{2} + k_{8} \cdot x_{1} + k_{12} \cdot k_{13}\right) + -1 \cdot k_{15} \cdot k_{7} \cdot x_{2}\right) / k_{15}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{15} \cdot \left(k_{9} / k_{12} \cdot x_{1} \cdot x_{2} / \left(k_{10} \cdot k_{12} + x_{1}\right) + k_{14}\right) + -1 \cdot k_{15} \cdot k_{11} \cdot x_{3}\right) / k_{15}