The effect of field fluctuation on a macromolecular system.

Abstract The Brownian motion of small ions in a solution produces fluctuating electric potential and field. If a molecule put in the solution can assume two states, of which the free energy depends on the field, the state of the molecule fluctuates according to the fluctuating field. The problem is formulated as a reversible reaction in the fluctuating environment. The effect of fluctuation on the rate constants and the average probability of the molecule in each state is estimated. The coupling between fluctuations of the field and the molecule is analysed, taking into consideration the space and time correlation of those fluctuations. Apparent correlation appears between the states of independent molecules in the solution due to the correlating fluctuation of the field around those molecules. The theoretical result is available for estimation of the probability of spontaneous response of the cell membrane without specific input. Special importance of such a field fluctuation is expected in the biological system because of its capacity to amplify and digitalize the effect of fluctuation.