Stabilization of energy charge, generation of oscillations and multiple steady states in energy metabolism as a result of purely stoichiometric regulation.

A simple kinetic model of cell energy metabolism with autocatalytic reaction sequences has beepn analysed. The model accounts for the fact that part of energy produced in the form of ATP, or any other equivalent form, is utilized in "sparking" reactions to activate initial substrates. Analysis of the model shows that energy metabolism, in the absen-e of all non-stoichiometric (i.e. isosteric, cooperative, and allosteric) regulations, is capable of (a) stabilizing, to a high degree of accuracy, the relative concentration of the "charged form" of the energy-transferring cofactor (ATP); (b) alternating between two stable stationary states by means of hysteretic transitions; (c) generating self-oscillations in energy production. It is proposed that energy metabolism can be a source of very slow, in particular circadian (of about a one-day period), oscillations which may serve as the basis for temporal organization of the cell.