Autonomous Energy Transducer: Proposition of a dynamical mechanism for conversion of energy at a molecular scale

How is energy converted from one form to another in order for a molecular machine to work? This question was addressed by Oosawa, who proposed that the coupling from chemical energy to mechanical work is not tightly fixed, but rather loose, in order that the molecular machine works under large thermal fluctuations although the amount of input energy is as small as an order of thermal fluctuations.

Inspired by this problem, we propose a fluctuating flexible machine described by a dynamical system with a few degrees of freedom, composing of a head with internal degrees of freedom, and a lattice. By numerical simulations of this simple model, we find that after excitation of some part of the system, energy is stored for some time, and is used step by step, allowing the head to move directionally along the lattice. The system can adjust the timing for its motion by itself, by taking advantage of internal dynamics. The obtained results provide a theoretical description for dynamics of the above `loose coupling' mechanism.