Do biological molecular machines act as Maxwell's demons?

Abstract

The nanoscopic isothermal machines are not only energy but also information transducers. We show that the generalized fluctuation theorem with information creation and entropy reduction can be fulfilled for the enzymatic molecular machines with the stochastic dynamics, which offers a choice of the work performance in a variety of ways. A model of such dynamics, specified by a critical complex network, is investigated. The main conclusion of the study is that the processing of free energy has to be distinguished from the processing of organization, which we identify with an adequately defined thermodynamic variable. Maxwell's demon utilizes entropy reduction for creation of information, which, from the former point of view, may be used for a reduction of energy losses, hence ultimately, for the performance of work. From the latter point of view, however, it can be used for other purposes, for example molecular recognition. This can be the case of biological molecular machines. From the biological perspective, the ascertainment is important, that the information creation and storage take place in the long lasting transient stages before completing the free energy transduction cycles. From a broader physical perspective, a supposition could be of special importance, that information is a change of organization, the thermodynamic function of state of the system.