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
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.[2] 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. Such organisms can withstand above 50 °C temperatures as they usually live within environments of 85 °C and above.
Uses and applications
Polymerase chain reactions
Thermostable enzymes such as Taq polymerase and Pfu DNA polymerase are used in polymerase chain reactions (PCR) where temperatures of 94 °C or over are used to melt DNA strands in the denaturation step of PCR.[10] This resistance to high temperature allows for DNA polymerase to elongate DNA with a desired sequence of interest with the presence of dNTPs.
Feed additives
Enzymes are often added to animal feed to improve the health and growth of farmed animals, particularly chickens and pigs. The feed is typically treated with high pressure steam to kill bacteria such as Salmonella. Therefore the added enzymes (e.g. phytase and xylanase) must be able to withstand this thermal challenge without being irreversibly inactivated.[11]
Protein purification
Knowledge of an enzyme's resistance to high temperatures is especially beneficial in protein purification. In the procedure of heat denaturation, one can subject a mixture of proteins to high temperatures, which will result in the denaturation of proteins that are not thermostable, and the isolation of the protein that is thermodynamically stable. One notable example of this is found in the purification of alkaline phosphatase from the hyperthermophile Pyrococcus abyssi. This enzyme is known for being heat stable at temperatures greater than 95 °C, and therefore can be partially purified by heating when heterologously expressed in E. coli.[12] The increase in temperature causes the E. coli proteins to precipitate, while the P. abyssi alkaline phosphatase remains stably in solution.
Glycoside hydrolases
Another important group of thermostable enzymes are
Approaches to improve thermostability of proteins
Thermostable toxins
Certain
See also
- Thermophiles
References
- S2CID 27832389.
- PMID 30443573.
- PMID 8875639.
- PMID 15576355.
- PMID 16332790.
- S2CID 2717885.
- PMID 2671995.
- PMID 10390356.
- PMID 15169774.
- PMID 2448875.
- PMID 32410091.
- PMID 11571149.
- .
- PMID 18812512.
- PMID 24352381.
- PMID 10544290.
- PMID 24280218.
- S2CID 21850845.
- PMID 11150616.
- PMID 26445442.
- PMID 12646689.
- PMID 25393107.
- PMID 9111013.
- PMID 21840396.
- S2CID 85654007.
- PMID 33723379.
- S2CID 85415249.
- PMID 33552459.
- ^ Aleccia JN (4 November 2011). "FDA: Moldy applesauce repackaged by school lunch supplier". NBC News. Retrieved 15 April 2015.
External links
