Discriminatory Proofreading Regimes in Nonequilibrium Systems

We use ideas from kinetic proofreading, an error-correcting mechanism in biology, to identify new kinetic regimes in nonequilibrium systems. These regimes are defined by the sensitivity of the occupancy of a state of the system to a change in its energy. In biological contexts, higher sensitivity corresponds to stronger discrimination between molecular substrates with different energetics competing in the same reaction. We study this discriminatory ability in systems with discrete states that are connected by a general network of transitions. We find multiple regimes of different discriminatory ability when the energy of a given state of the network is varied. Interestingly, the occupancy of the state can even increase with its energy, corresponding to an antiproofreading regime. The number and properties of such discriminatory regimes are limited by the topology of the network. Finally, we find that discriminatory regimes can be changed without modifying any hard-wired structural aspects of the system but rather by simply changing external chemical potentials.