Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002
Far-from-equilibrium biochemical circuits
Department of Physics, Faculty of Natural Sciences, Mathematics and Education, University of Split, N. Tesle 12, HR-21000 Split, Croatia
Predicting behaviour of very complex networks of biochemical reactions is the next important goal after the completion of different genome projects. The consensus seem to be that some optimization principle based on any one (or several) of many proposed biological objective functions would help in reaching that goal. From the physical point of view life is very efficient entropy producer. Rather than looking for the optimization principle(s) from biology, we shall examine extremum principles for the entropy production, with a goal to find if any of them is able to predict strong observed fluxes in biochemical circuits that are important in cellular bioenergetics.
There are several possible approaches how to apply nonequilibrium thermodynamics to steady state biochemical circuits1,2, and in particular to photosynthesis3,4. Each of them is connected with some difficulties that will be discussed. We shall use our own method for calculating the entropy production and efficiency of several simple kinetic models for photon driven and ATP driven biochemical circuits operating in a far-from-equilibrium steady state. In particular, we shall show that maximal entropy production implies the optimization of the available power when the system works far from equilibrium, which is in accord with biological objectives.
1 D. A. Beard, S.-D. Liang, H. Qian, Energy Balance Analysis of Complex Metabolic Networks, Biophys. J. (2002), to be published.
2 T. L. Hill, Free Energy Transduction and Biochemical Cycle Kinetics, Spriger-Verlag, 1995, New York.
3 G. Meszena, H. W. Westerhoff, Non-equilibrium Thermodynamics of Light Absorption, J. Phys. A: Math. Gen. 32 (1999) 301-311.
4 C. D. Andriesse, M. J. Hollestelle, Minimum Entropy Production in Photosynthesis, Biophys. Chem. 90 (2001) 249-253.