Thermodynamic Molecular Switch in Sequence-Specific Hydrophobic Interaction: Two Computational Models Compared. (2003)

• Record Type: Journal Article
• Authors: Chun, Paul
• Other Names: Learmonth Robert P. Academic Editor.
• Is Part Of: TheScientificWorldjournal. Volume 3(2003)
• Page Start: 176
• Page End: 193
• Publication Date: 2003
• Subjects: sequence-specific hydrophobic interactions -- thermodynamic molecular switch -- Planck-Benzinger methodology; Science -- Periodicals; Technology -- Periodicals; Medicine -- Periodicals; 505
• DOI: 10.1100/tsw.2003.16
• Languages: English
• ISSNs: 2356-6140

Abstract

Abstract : We have shown in our published work the existence of a thermodynamic switch in biological systems wherein a change of sign in ΔCp°(T)reaction leads to a true negative minimum in the Gibbs free energy change of reaction, and hence, a maximum in the related Keq . We have examined 35 pair-wise, sequence-specific hydrophobic interactions over the temperature range of 273–333 K, based on data reported by Nemethy and Scheraga in 1962. A closer look at a single example, the pair-wise hydrophobic interaction of leucine-isoleucine, will demonstrate the significant differences when the data are analyzed using the Nemethy-Scheraga model or treated by the Planck-Benzinger methodology which we have developed. The change in inherent chemical bond energy at 0 K, ΔH°(T0 ) is 7.53 kcal mol -1 compared with 2.4 kcal mol -1, while ‹ts › is 365 K as compared with 355 K, for the Nemethy-Scheraga and Planck-Benzinger model, respectively. At ‹tm ›, the thermal agitation energy is about five times greater than ΔH°(T0 ) in the Planck-Benzinger model, that is 465 K compared to 497 K in the Nemethy-Scheraga model. The results imply that the negative Gibbs free energy minimum at a well-defined ‹ts ›, where TΔS° = 0 at about 355 K, has its origin in the sequence-specific hydrophobic interactions, which are highly dependent on details of molecular structure. The Nemethy-Scheraga model shows no evidence of the thermodynamic molecular switch that we have found to be a universal feature of biological interactions. The Planck-Benzinger method is the best known for evaluating the innate temperature-invariant enthalpy, ΔH°(T0 ), and provides for better understanding of the heat of reaction for biological molecules.