Space-Time Analysis of Assembly Trajectories

A useful analogy can be made between the statistical thermodynamics of configurations and the statistics of dynamical events in trajectories.

Specifically, we investigate the statistics of events such as the binding and unbinding of subunits, and how they are correlated in space and time. We consider averages over ensembles of dynamical trajectories, much like a thermodynamic average is taken over an ensemble of configurations.

Working with Rob Jack, now at the University of Bath, and David Chandler, at the University of California, Berkeley, we showed that the events that lead to malformed or disordered assembly structures can be identified by measuring correlation-response ratios that deviate equilibrium values dictated by the fluctuation-dissipation theorem. Our work suggests that weak binding free energies are a general requirement for successful assembly into an ordered low free energy product.

Association free energies that are large compared to the thermal energy, kBT, prevent the system from "locally" equilibrating between different metastable configurations (such as shown in Figure 3 on the right) during assembly. These conclusions are described in more detail in Ref. [3].