Thermostability

In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature.

Thermostable materials may be used industrially as fire retardants. A thermostable plastic, an uncommon and unconventional term, is likely to refer to a thermosetting plastic that cannot be reshaped when heated, than to a thermoplastic that can be remelted and recast.

Thermostability is also a property of some proteins. To be a thermostable protein means to be resistant to changes in protein structure due to applied heat.

Thermostable proteins

Most life-forms on Earth live at temperatures of less than 50 °C, commonly from 15 to 50 °C. Within these organisms are macromolecules (proteins and nucleic acids) which form the three-dimensional structures essential to their enzymatic activity. Above the native temperature of the organism, thermal energy may cause the unfolding and denaturation, as the heat can disrupt the intramolecular bonds in the tertiary and quaternary structure. This unfolding will result in loss in enzymatic activity, which is understandably deleterious to continuing life-functions. An example of such is the denaturing of proteins in albumen from a clear, nearly colourless liquid to an opaque white, insoluble gel.

Proteins capable of withstanding such high temperatures compared to proteins that cannot, are generally from microorganisms that are hyperthermophiles.