A thermodynamic approach to energy transduction in mitochondria

Abstract

A model based on non-equilibrium thermodynamics has been extended for investigation of energy transduction in biological systems. Rate of free energy loss and efficiency of some mitochondria in energetic and thermogenic modes have been determined by means of this model. The theoretical results are in agreement with previous experimental ones indicating that the rate of free energy loss is greater in mitochondria with thermogenic function while the efficiency of oxidative phosphorylation appears to be less than energetic ones. Therefore, the model illustrates the principle that mitochondria with energetic role are able to store more energy in the form of adenosine triphosphate (ATP), while mitochondria with thermogenic function release more energy as heat and are thus less efficient in energy storage. Furthermore, the model introduces some thermodynamic criteria that can provide valuable information on whether the mitochondrion is functioning properly. After evaluation of some parameters for each mitochondrion, these criteria can be easily determined by means of the presented equations. Hence, the developed model can be widely used in medical, pharmaceutical, and biological studies.