Oscillations in Open Systems

Cooperativity in enzyme action and servomechanism-type control of enzyme activity are important principles of metabolic control which we have already encountered. Separately or in concert, they introduce nonlinearity into the kinetic behavior of a pathway. It is noteworthy that nonlinearity is at the heart of the genesis of oscillations as well. 

This is a result of autocatalytic or feedback phenomena in systems where components are extensively coupled, so that collective behavior becomes possible. Servomechanisms in biological systems act as closed loops in which the output feeds back upon the input, modifying the kinetics of the process. Far-from-equilibrium conditions are a prerequisite for any state in which we will encounter oscillatory behavior. The implications seem clear that oscillatory phenomena can propagate signals which can be amplified and can stimulate other, similar systems, which can then act collectively. The occurrence of oscillatory phenomena in biochemical systems has been documented (Chance et al., 1973 Nicolis and Portnow, 1973) however, as yet, there is no conclusive proof that such phenomena actually generate signals responsible for such hierarchical behavior. 

As discussed in Chapter 2, the ability of living organisms to utilize energy and matter to form dissipative structures beyond the thermodynamic branch is crucial to the ordering of the life process. Oscillatory behavior around a steady state of a biochemical pathway is an example 

---