How do I write code of stochastic model for this gene expression?

I’ve very little knowledge of Biology. I want to write code (in MATLAB) for “The repressilator” explained in very famous paper "A synthetic oscillatory network of transcriptional regulars" by Michael B. Elowitz & Leibler. I have written code using deterministic approach but I don't know how to stochastic part. I am trying to solve it with Gillespie's algorithm but I don’t understand what reaction is producing what. Any help?

[Andrew Newell]

Sounds like you need help with the mathematical and chemical part. We're here to help you with problems in MATLAB code, once you have some.

[Luqman Saleem]

God. I hate Chemistry and Biology.