Fig. 8.

Phase diagram of optimal expression dynamics for an IMA network. Each point in the graph corresponds to a pair of values (γ, η/T) represents an optimization of the cost function over the regulatory parameters. Each solution was classified on the basis of the resulting enzyme expression dynamics. The red region corresponding to intermediate values of the evolutionary parameters shows a pattern of separation of enzyme dynamics before and after the regulatory metabolite. The green region consists of parameters where the optimal solution involved no regulation at all, whereas the blue region contains other types of expression patterns. The blue region is likely to involve unrealistic parameter values because these solutions typically involve fold changes of over 10⁴.