Dynamics and thermodynamics of open chemical networks

Open chemical networks (OCN) are large sets of coupled chemical reactions where some of the species are chemostated (i.e. continuously restored from the environment). Cell metabolism is a notable example of OCN. Two results will be presented. First, dissipation in OCN operating in nonequilibrium steady-states strongly depends on the network topology (algebraic properties of the stoichiometric matrix) \footnote{M. Polettini and M. Esposito, J. Chem. Phys. 141, 024117 (2014)}. An application to oligosaccharides exchange dynamics performed by so-called D-enzymes will be provided \footnote{R. Rao, D. Lacoste and M. Esposito, arxiv:1509.07446}. Second, at low concentration the dissipation of OCN is in general inaccurately predicted by deterministic dynamics (i.e. nonlinear rate equations for the species concentrations). In this case a description in terms of the chemical master equation is necessary. A notable exception is provided by so-called deficiency zero networks, i.e. chemical networks with no hidden cycles present in the graph of reactant complexes \footnote{M. Polettini, A. Wachtel and M. Esposito, arxiv:1507.00058}.