3 larger than that of the metastable form, and they computed the pressure-volume (PV) expansion work associated with this expansion, which comes to only 0.006 kcal mol -1 . We obtained a similar volume change, 5 Å 3 , for this step, by examining the time-series of system volumes in our explicit solvent simulations run at room pressure. However, it is the rotary work available from these motors, not the PV work that should be of interest. This may be understood by considering that capturing work done by the motor involves coupling an external load to the angle between the stator and rotor, not to a change in volume. More broadly, it is also worth noting that the Gibbs free energy change is the maximal non-PV work in a constant-temperature, constant-pressure, closed system.