THEORETICAL APPROACHES TO THE EVOLUTIONARY OPTIMIZATION OF GLYCOLYSIS- CHEMICAL-ANALYSIS

In the first part of this work [Heinrich, R., Montero, F., Klipp, E., Waddell, T. G. & Melendez-Hevia, E. (1997) Eur. J. Biochem. 243, 191-2 01] the kinetic and thermodynamic constraints under which an optimal g lycolysis must be designed have been analysed. In this second part, we present a chemical analysis of the glycolytic pathway in order to det ermine if its design is chemically optimized according the possibiliti es that a glycolytic design can have. Our results demonstrate that gly colysis in modern-day cells (from glucose to lactate) has an optimized design for maximizing the flux of ATP production, and a thermodynamic profile which guarantees a high kinetic efficiency. We also discuss s ome cases of paleometabolism for this pathway as alternative metabolic pathways, less optimized, that exist in some bacteria. Our analysis r elates mainly to metabolism designed under constant chemical affinity (substrates and products of the pathway constant), where the target of optimization can be the flux of ATP production. We also discuss the c ase of an externally imposed input flux, whose target of optimization is the stoichiometric yield of ATP.