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The Planck-Benzinger thermal work function: Determining the thermal set point in interacting biological systems

Authors

  • Paul W. Chun

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610-0245
    • Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610-0245
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Abstract

One of the more interesting discoveries in recent studies of biological thermodynamics concerns the way in which application of the Planck–Benzinger methodology allows one to evaluate how the thermal set point of a biological system is established and maintained on a molecular level. Macromolecular interactions will always exhibit a negative minimum value of the Gibbs free energy change at a well-defined temperature, <TS>, which may be defined as the thermal set point. Each interacting biological system will have its own unique value of <TS> where the bound unavailable energy TΔS0 = 0. In the human body, that thermal set point is 37°C. At the thermal set point, the maximum work can be accomplished and the system is at its most stable. Each interacting biological system examined by the Chun method confirms the existence of a thermodynamic molecular switch wherein a change of sign in ΔCp0(T) leads to true negative minimum in the Gibbs free energy change of reaction, and hence a maximum in the related equilibrium constant, Keq. Application of the Planck–Benzinger methodology has demonstrated that there is a lower cutoff point, <Th>, where entropy is favorable but enthalpy is unfavorable, and an upper cutoff, <Tm>, above which enthalpy is favorable but entropy unfavorable. Only between these two limits, where ΔG0(T) = 0, is the net chemical driving force favorable for such biological processes as protein folding, protein–protein or protein–nucleic acid interaction and protein self-assembly. In examining interacting biological systems, the thermal set point will vary from one organism to another, but TΔS0, the bound unavailable energy, will always be equal to zero. It is apparent from Chun's extensive studies of biological interactions that the origins of life in any chosen system are inevitably linked to a single, unique thermal set point. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

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