Robustness and parameter geography in post-translational modification systems
Fig 2
Reaction network and example enzyme mechanism for a two-site PTM system.
A two-site PTM system is shown, in which modification and demodification are sequential and in which each enzymatic step yields a single product (“distributivity”). The box on the right shows an example of an enzyme mechanism made up from the elementary reactions in the grammar in Eq 1, illustrating multiple routes and multiple intermediate enzyme-substrate complexes. This example is weakly irreversible: the product S1 can bind to E but cannot be converted back into substrate S0, so that the mechanism is irreversible overall.