Thermodynamics of Biologies

For cells the processes of adhesion and spreading on surfaces, are two distinctly separate processes. To date, only adhesion has been described in a thermodynamic way. Cell spreading, on the other hand, is difficult to describe in this manner, due to cellular activity, such as protein production and cytoskeleton transport which complicate the spreading process. As a result, the strength of adhesion does not correlate well with the 

The free energy change for adhesion of cells from a liquid suspension onto a solid substrate is given by 

Discuss with your neighbor how protein adsorption can still be spontaneous (AG 0), even though some of these processes are endothermic (AH 0). Look up values for the solid surface energies of the two substrates in Appendix 4 (you may have to select similar materials, but this is sufficient for these purposes). How do these enthalpies compare in magnitude to the respective surface energies  

The corresponding receptor densities are n,T = RiT/Ai,ni, = B/Ac, ntc = RiJAc, and Uio = RioKAi - Ac), where A, is the total surface area of cell i and Ac is the contact area. We will assnme that the distance between the cell membranes is constant and eqnal to 5. 

Chemical and Process Thermodynamics, 3rd ed., Prentice-Hall, Upper Saddle River, NJ, 1999. 

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Nowadays, studies of direct electrochemistry of redox proteins at the electrodesolution interface have held more and more scientists interest. Those studies are a convenient and informative means for understanding the kinetics and thermodynamics of biological redox processes. And they may provide a model for the study of the mechanism of electron transfer between enzymes in biological systems, and establish a foundation for fabricating new kinds of biosensors or enzymatic bioreactors. 

Jon, D., and J. E. Llebot, Introduction to the Thermodynamics of Biological Processes, Prentice-Hall, Englewood Cliffs, NJ, 1990. 

Lamprecht, I. and Zotin, A.I. (eds), 1978. Thermodynamics of Biological Processes. Walter de Gruyter, Berlin, 428 pp. 

Prigogine, I., and I. Stengers. Order out of Chaos. Toronto Bantam Press, 1984. [A comparatively accessible treatment of the thermodynamics of biological systems. Prigogine won the 1977 Nobel Prize in chemistry for his pioneering work on the thermodynamics of complex systems.]... 

Nevertheless, voltammetric techniques have long been applied to the study of direct electron transfer processes of biological molecules. Such early voltammetric studies revealed a high degree of electrochemical irreversibility in the direct heterogeneous electron transfer reactions between electrodes and biological molecules. The irreversible nature of direct electron transfer observed in these early studies precluded the accurate and precise characterization of the electron transfer stoichiometry and thermodynamics of biological molecules. The models alluded to above were often used to account for the irreversible electron transfer kinetics observed in these studies. 

Since the first report of the application of mediated ottle to the study of the redox properties of biological molecules, the technique has been widely used for this purpose. Table 1 summarizes this body of work. A number of novel applications of ottle described in this table have served to provide new insights into the thermodynamics of biological molecule redox reactions. One of these applications is described in some detail in the following discussion. 

Garcia HG, Kondev J, OrmeNetal (2011) Thermodynamics of biological processes. Methods Enzymol 492 27-59. doi 10.1016/B978-0-12-381268-1.00014-8... 

Section 26.4 Bioenergetics is concerned with the thermodynamics of biological processes. 

Another very valuable tool in arsenal of theoretical investigation of biological molecules is the method of molecular dynamics simulations. This computational method describes the time dependent behaviour of the given molecular system. To date an extensive use of molecular dynamics simulations has resulted in generation of a wealth of detailed information on the fluctuations and conformational changes of proteins and nucleic acids. Such methods are now routinely used to investigate the stracture, dynamics and thermodynamics of biological molecules and their complexes [48-50, 65-71, 85]. 

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