Species vs. label half-life. Panel A: The species half-life of a substrate S in the reaction S → P is plotted for different reaction types (solid lines). Except for processes of order 1, the half-life is time-dependent. Since the substrate is not produced in further reactions, the label half-life (dashes) equals the species half-life. Panel B: The substrate S participates in a production (A → S) and a processing (S → P ) reaction. Now, the species half-life differs except for a linear processing from the label half-life, because the label flux is proportional to the total flux of each reaction and is therefore affected by concentration changes through influx of S. Both panels: The species half-life has been determined analytically and numerically according to the methods section. Matlab scripts to reproduce the plots are available in the additional file 1.
Maiwald et al. BMC Systems Biology 2012 6:13 doi:10.1186/1752-0509-6-13