Proteins heating reversibly increases

Heating Reversibly Increases Protein Order, an Inverse Temperature Transition... 

In summary, formalin-treated does not significantly perturb the native structure of RNase A at room temperature. It also serves to stabilize the protein against the denaturing effects of heating as revealed by the increase in the denaturation temperature of the protein. However, formalin-treatment does not stabilize RNase A sufficiently to prevent the thermal denaturation of the protein at temperatures used in heat-induced AR methods as shown by both DSC and CD spectropolarimetry. This denaturation likely arrises from the heat-induced reversal of formaldehyde cross-links and adducts, as shown in Figure 15.4 of Section 15.4. Further, cooling formalin-treated RNase A that had been heated to 95°C for 10 min does not result in the restoration of the native structure of the protein, particularly in regard to protein tertiary structure. 

Spider silk proteins from plants remain soluble at high temperatures, allowing them to be enriched by boiling [26]. In order to enrich the spider silk-ELP fusion protein, we therefore exposed tobacco leaf extracts to heat treatment at 95°C for 60 min and then cleared the supernatant by centrifugation. In further steps, the reversible precipitation behavior of ELP fusion proteins was exploited to develop a suitable purification strategy. For the selective precipitation of SOl-lOOxELP, NaCl was added at a final concentration of 2 M and the temperature was increased to 60 °C. In this man-... 

The double helix can be denatured by heating (melting). Denatured DNA, like denatured protein, loses its structure, and the two strands separate. Melting of DNA is accompanied by an increase in the absorbance of UV light with a wavelength of 260 nm. This is termed hyperchromicity and can by used to observe DNA denaturation. DNA denaturation is reversible. When cooled under appropriate conditions, the two strands find each other, pair correctly, and reform the double helix. This is termed annealing. 

One expects a significant amount of both the native and denatured protein structure in the vicinity of these two temperatures. The disruption of the native state on heating is usually called heat denaturation, since it proceeds with heat absorption and, consequently, with an increase in the molecular enthalpy and entropy. The disruption of the native structure on cooling, which we can call by analogy cold denaturation, should then proceed with a release of heat and, hence, with a decrease in enthalpy and entropy, because both of these functions have reversed their signs before reaching temperature 7 en. ... 

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