TRANSITIONS AND NEW DYNAMICAL STATES INDUCED BY NOISE IN A MULTIPLY REGULATED BIOCHEMICAL SYSTEM

Noise-induced transitions between coexisting states, and the emergence of a new oscillatory state, are examined in a model for a multiply re gulated biochemical system. For the undisturbed system, three oscillat ory states, I, II, and III, coexist. It is found that noise above a cr itical amplitude can cause a transition between states III and II and between states III or II and state I, whereas a transition from state I to either states TI or III is never observed. This indicates that th e relative stability under noise perturbations is greatest for state I , and progressively less for states II and III. In addition to this tr ansition behaviour, a purely noise-induced state is found. Under noise perturbations, the average concentration of metabolites may depend on both the time duration and amplitude of the superimposed noise. The i mplications of these results for understanding the in vivo behaviour o f complex biochemical systems are discussed. (C) 1997 Elsevier Science B.V.