FIGURE 4.

Conserved pools and extreme pathway classifications. (A) Type I, II, and III extreme pathways correspond to through pathways, futile cycles coupled to cofactor utilization, and internal loops that are thermodynamically infeasible (Beard et al., 2002; Price et al., 2002), respectively. (B) Type A, B, and C metabolic pools correspond to the conservation of biochemical elements, metabolic moieties common to the primary and secondary metabolites, and cofactor conservation, respectively. Systems shown are presented as schematic examples of pools and flux pathways.