Planck–Benzinger thermal work function in biological systems


  • Paul W. Chun

    1. Department of Biochemistry and Molecular Biology, Box 100245, University of Florida College of Medicine, Gainesville, Florida 32610-0245, USA
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The Planck–Benzinger methodology provides a means of determining the innate temperature-invariant enthalpy and thermal agitation energy, or the heat capacity integrals, math image ΔCp°(T)dT, and allows precise determination of 〈TCp〉, 〈Th〉, 〈Ts〉, and 〈Tm〉. It is a method for evaluating [ΔHmath image − ΔH°(T0)], the heat of reaction for biological molecules at room temperature. The results imply that the negative Gibbs free energy change minimum at a well-defined stable temperature, 〈Ts〉, where the bound unavailable energy TΔS° = 0, has its origin in the sequence-specific hydrophobic interactions. Each case confirms the existence of a thermodynamic molecular switch wherein a change of sign in ΔCp°(T)reaction leads to true negative minimum in the Gibbs free energy change of reaction and, hence, a maximum in the related equilibrium constant, Keq. At this temperature, 〈TS〉, ΔH°(TS)(−) = ΔG°(TS)(−)min, the maximum work can be accomplished in biological systems. Application of the Planck–Benzinger methodology to biological systems has demonstrated a basic rule for life processes, in that there is a lower cutoff point, 〈Th〉, where entropy is favorable but enthalpy is unfavorable, that is, ΔH°(Th)(+) = TΔS°(Th)(+), and an upper cutoff, 〈Tm〉, above which enthalpy is favorable but entropy unfavorable, that is, ΔH°(Tm)(−) = TΔS°(Tm)(−). Only between these two limits, that is, where ΔG°(T) = 0, is the net chemical driving force favorable for such biological processes as protein folding; protein–protein, protein–nucleic acid or protein-membrane interactions; and protein–self-assembly. Indeed, all interacting biological systems examined using the Planck–Benzinger methodology have shown such a thermodynamic switch at the molecular level, suggesting that its existence may be universal. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004