Quantitative analysis of the Hopf bifurcation in the Goodwin n-dimensional metabolic control system.

We study, from a quantitative point of view, the Hopf bifurcation in an ODE model of feedback control type introduced by Goodwin (1963) to describe the dynamics of end-product inhibition of gene activity. We formally prove that the exchange of linear stability of the positive equilibrium in the n-dimensional Goodwin system with equal reaction constants coexists with a Hopf bifurcation of nontrivial periodic solutions emanating from this equilibrium, without any further restriction on the dimension n greater than or equal to 3 or on the Hill coefficient. The direction of the bifurcation and the stability and the period of the bifurcating orbits are estimated by means of the algorithm proposed by Hassard et al. (1981).