Calculation of the averaged relative error

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Equilibrium constant

The only steps for which an error on the equilibrium constant is really measured is the phosphorylation by creatine kinase and the activation of C3G Therefore this relative error is calculated and assumed as relative error for the reactions for which no hint about the uncertainty is given in the literature. (Reactions are: Ras-Activation and Inactivation as well as Rap1-Activation and Inactivation)

$\sigma = \frac{\frac{7}{177}+\frac{20.2951}{74.1043}}{2} = 1.5671 \cdot 10^{-1}$

Assoziation

There are experimental errors on the binding of EGF to EGFR and of Sos to EGFR. The relative error of these two reactions is averaged.

$\frac{\frac{0.24}{1.07} + \frac{61.131}{147}}{2} = 0.320687$

Dissoziation

There are experimental errors on the binding of EGF to EGFR and of Sos to EGFR. The relative error of these two reactions is averaged.

$\frac{\frac{5.91\cdot 10^{-4}}{2.38\cdot 10^{-3}} + \frac{3.965\cdot 10^{-2}}{1.488\cdot 10^{-1}}}{2} = 0.257392$

k_cat

For the calculation of the averaged relative error four reactions are taken into account (Mek-Activation(BRaf), Raf1-Removal and both Sos-Removal steps).

For the Mek-activation and Raf1-Removal process, the actual relative error without any further transformation is used.

$\frac{\frac{0.0159386}{0.25083} + \frac{0.64133}{1.9248} + \frac{0.011}{31.6} + \frac{0.109}{6.99} }{4} = 0.10395$

K_m

The same reaction as for k_cat are taken into account, plus the second step of the Erk-activation and inactivation process.

$\frac{\frac{6.6\cdot 10^{-3}}{4.66\cdot 10^{-2}} + \frac{1.3348\cdot 10^{-1}}{1.5} + \frac{8.984}{42.7} + \frac{0.667398}{0.275} + \frac{62}{656} + \frac{691}{2800}}{6} = 0.53485$