BRaf and Raf1-Activation

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Binding Reaction

BRaf-Activation:

$\text{BRaf} + \text{activeRap1} \rightleftharpoons \text{BRafPP} + \text{activeRap1}$

Raf1-Activation:

$\text{Raf1} + \text{activeRas} \rightleftharpoons \text{Raf1PP} + \text{activeRas}$

Kinetic equation

BRaf-Activation:

$v_{\text{BRaf-Activation}} = \frac{k_{cat} \cdot [\text{activeRap1}] \cdot [\text{BRaf}] \cdot (1-\frac{[\text{BRafPP}]}{[\text{BRaf}] \cdot K_{eq}})}{Km_{\text{BRaf}} \cdot (1 + \frac{[\text{BRaf}]}{Km_{\text{BRaf}}} + \frac{[\text{BRafPP}]}{Km_{\text{BRafPP}}})}$

The activation of BRaf by Ras is modelled in the same way as the one by Rap1.

Raf1-Activation:

$v_{\text{Raf1-Activation}} = \frac{k_{cat} \cdot [\text{activeRas}] \cdot [\text{Raf1}] \cdot (1-\frac{[\text{Raf1PP}]}{[\text{Raf1}] \cdot K_{eq}})}{Km_{\text{Raf1}} \cdot (1 + \frac{[\text{Raf1}]}{Km_{\text{Raf1}}} + \frac{[\text{Raf-1PP}]}{Km_{\text{Raf1PP}}})}$

final Parameter

	Raf1	BRaf (Rap1)	BRaf (Ras)
kcat [1/s]
mean [1/s]	17.658	17.2111	5.85846
std [1/s]	3.0997	3.0213	1.0284
Km [μM]
mean [μM]	5.42275 * 109	9.66527 * 109	2.43218 * 109
std [μM]	2.6674 * 109	4.5458 * 109	1.1439 * 109

Parameter

The same values as in the model by Xu et al (2010) are used and the standard deviation is calculated by assuming the same averaged relative error as for the measured values.(Calculation of the averaged relative error)

Km_P value and equilibrium constant

The K_m value for the product is assumed to be similar to but slightly smaller than the the K_m value of the substrate because of the similarity of the both species. Therefore the K_m value of the substrate is multiplied by 0.95 to gain the one of the product and the uncertainty is increased by increasing the error on Km_substrate by 50%.

For information about the equilibrium constant please see here.