Table 1

Model parameters for convenience kinetics
Parameter	Symbol	unit	item in graph	energy interpretation

Energy constant		1	metabolite	metabolite formation
Velocity constant		1/s	reaction	transition state
Michaelis-Menten constant		mM	arrow reaction – substrate	substrate binding
Activation constant		mM	arrow reaction – activator	activator binding
Inhibition constant		mM	arrow reaction – inhibitor	inhibitor binding
Metabolite concentration	c_i	mM	metabolite
Enzyme concentration	E_l	mM	reaction

The system parameters (top) are thermodynamically independent. Their numerical values can be written as exp(G/RT) where G denotes either a Gibbs free energy or a difference of Gibbs free energies. The corresponding molecular processes are listed in the last column. In contrast to the system parameters, enzyme and metabolite concentrations (bottom) can easily fluctuate over time; we call them state parameters.
Liebermeister and Klipp Theoretical Biology and Medical Modelling 2006 3:41 doi:10.1186/1742-4682-3-41