This is a model of a branched pathway with sequential feedback, described

in Hofmeyr, J.-H. S. (1986), Comput. Aplic. Biosci. 2, 243-249.

In the report, look for the Stability Analysis section and note that two

eigenvalues are a complex conjugate pair. This indicates that

variable perturbations relax back to the steady state with one oscillatory

component. If you plot the time course for the fluxes and metabolites concentrations you will see that they have either a maxima or a minima,

which are part of the the first cycle (but because it is very damped it is

also the last).