Dynamics of Controlled Metabolic Network and Cellular Behaviour

Abstract

The existence of elaborate control mechanisms for the various biochemical processes inside and within living cells is responsible for the coherent behaviour observed in its spatio-temporal organisation. Stability and sensitivity are both necessary properties of living systems and these are achieved through negative and positive feedback loops. We have studied a three-step reaction scheme (i) with endproduct inhibition, and, (ii) with allosteric activation coupled to endproduct inhibition, to observe the variety of behaviour exhibited by the systems under different conditions. The more complex system showed a wider variety of behaviour comprising of steady state, simple limit cycle, complex oscillations, and period bifurcations leading to chaos. This system also shows the existence of two distinct chaotic regimes under the variation of a single parameter. In comparison, the single loop system showed only steady, bistable and periodic behaviour. The variety of functions observed in living systems may be controlled by the interplay of few basic processes -the higher the level of complexity of the network, more diverse is the behaviour.