We have been building a model coupling electrophysiology and signal transduction using expanded NEURON. In our debugging process, we decided to validate the modeling of the chemical reactions with another simulator. Simulation results with NEURON are wrong as soon as we introduce enzymatic reactions with KINETIC blocks.

We read this thread viewtopic.php?p=1667 where numerical instability is mentioned in the last message. This doesn't seem to be our problem. We do however use variables in the rate constants. This is an example in which variables are used to compute a dynamic rate parameter based on Michaelis-Menten:

Code: Select all

```
tempRaf = ((kcat_raf * RasGTPi)/(Rafi + km_raf))
tempRafP = (kcat_rafP * RafPhosphatase)/(RafPi + km_rafP)
~ Rafi <-> RafPi (tempRaf, tempRafP)
```

What is wrong with this?