Inverse temperature transitions endothermic/exothermic

Relative Magnitude of the Endothermic and Exothermic Components of the Inverse Temperature Transition and Relevance to Biology s Protein-based Machines... 

Figuke 8.1. Component heats of hydrophobic association of an inverse temperature transition obtained by means of temperature-modulated differential scanning calorimetry (TMDSC). (Upper curve) An exothermic component of the inverse temperature transition due to the physical (van der Waals) interaction between associating molecules. (Middle curve) The endothermic component (due to disruption of hydrophobic hydration), which is the fundamental feature of an inverse temperature transition of hydrophobic association. (Lower curve) Net endothermic heat of an inverse temperature transi-... 

Jones 6-12 potential or the Buckingham potential functions. It will be interesting, in future work, to determine the relative magnitude of the endothermic and exothermic components for each of the amino acid residues and for other biologically relevant chemical modifications, as they contribute as guest residues to the inverse temperature transition of (GVGVP) and of other informative host model proteins. 

J.C. Rodrfguez-Cabello, J. Reguera, M. Alonso, T.M. Parker, D.T. McPherson, and D.W. Urry, Endothermic and Exothermic Components of an Inverse Temperature Transition for Hydro-phobic Association by TMDSC. Chem. Phys. Lett., 388,127-131,2004. 

Remarkably, Butler found the dissolution of oil-like groups to be exothermic. Therefore, the reverse reaction for loss of hydrophobic hydration must be endothermic. The reaction attending the inverse temperature transition to hydrophobic association is indeed endothermic as shown by differential scanning calorimetry data, specifically the middle curve in Figure 8.1 and the curves in Figure 7.1. 

Formation of hydrophobic hydration is exothermic (Butler, 1937). Accordingly, when the temperatiure of the dissolved protein with its hydrophobic hydration is raised from below to above the inverse temperature transition, an endothermic transition due to the conversion of hydrophobic hydration to bulk water occurs. The transition from hydrophobic hydration to bulk water represents a positive change in entropy. By finding a suitable solvent that allows the transition but reduces the heat of the transition to near zero, it becomes possible to determine whether a decrease in elastic... 

Differential thermal analysis (DTA) is a thermal technique in which the temperature of a sample, compared with the temperature of a thermally inert material, is recorded as a function of the sample, inert material, or furnace temperature as the sample is heated or cooled at a uniform rate. Temperature changes in- the sample are due to endothermic or exothermic enthalpic transitions or reactions such as those caused by phase changes, fusion, crystalline structure inversions, boiling, sublimation, and vaporization, dehydration reactions, dissociation or decomposition reactions, oxidation and reduction reactions, destruction of crystalline lattice structure, and other chemical reactions. Generally speaking, phase transitions, dehydration, reduction, and some decomposition reactions produce endothermic effects, whereas crystallization, oxidation, and some decomposition reactions produce exothermic effects. 

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