Pathway Thermodynamics Highlights Kinetic Obstacles in Central Metabolism
Figure 4
Schematic representation of the interplay between the net reaction flux and the internal and external (i.e., overall or net) energetic profiles.
ΔrG′ corresponds to the driving force of the net reaction (which depends on the concentrations of the substrates and products); ΔG‡fwd to the thermodynamic barrier of the forward reaction, associated with the binding of the substrates and with the different reaction intermediates formed during catalysis; and ΔG‡bwd corresponds to the thermodynamic barrier of the backward reaction, associated with the different reaction intermediates formed during catalysis and with the release of the products. All reactions are assumed to be catalyzed by the same amount of enzyme units. (A) High internal thermodynamic barrier and high thermodynamic driving force. (B) High internal thermodynamic barrier and low thermodynamic driving force. (C) Low internal thermodynamic barrier and low thermodynamic driving force. (D) Low internal thermodynamic barrier and high thermodynamic driving force.