Author(s): Purevdolgor Luvsantseren, Khenmedeh Lochin, Enkhbayar Purevjav
Dynamic model of cell cycle from G1 to S stage is described by a system of six ordinary differential equations. These equations display the rate of changes in concentrations of proteins, cyclin E, CycE, cyclin dependent kinase, CDK2 and protein phosphatase, CDC25. We have developed a stochastic model of G1ï®S transition of cell cycle on the basis of the above mentioned dynamic model. The model is realized by the Gillespie algorithm of stochastic simulation using the Matlab 7.0 and FORTRAN 95. Scaling factor converts the normalized concentration of the dynamic model to the number of molecules of the stochastic model. The increase of scaling factor is related to the increasing number of the molecules of CycE, inactive CycE/CDK2 complex, active CycE/CDK2 complex, and mono and dephosphorylated CDC25. Solutions of this model show limit cycle depending on the time. When scaling factor is small the solution shows drastic random fluctuations. The solutions of the stochastic model is approached to the solutions of dynamic model, especially, when the scaling factor is more than two hundred (â¦=200). In this case, fluctuations of periods of limit cycle are stabilized.
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