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Thermostability

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Title: Thermostability  
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Subject: Extremophile, Fast parallel proteolysis, Nucleoplasmin, Ectotherm, Endotherm
Collection: Extremophiles, Protein Structure, Toxicology
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Thermostability

Thermostability is the quality of a substance to resist irreversible change in its chemical or physical structure 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 also commonly refers to a protein resistant to change in its protein structure due to applied heat.

Contents

  • Thermostable proteins 1
    • Approaches to improve thermostability of proteins 1.1
  • Thermostable toxins 2
  • See also 3
  • External links 4
  • References 5

Thermostable proteins

Most life-forms on Earth live at temperatures of less than 50 °C, commonly from 15 to 50 °C. Above this, thermal energy may cause the unfolding of the protein structure, where the activity of the protein is abolished and a condition understandably deleterious to continuing life-functions. The denaturing of proteins in albumen from a clear, nearly colourless liquid to an opaque white, insoluble gel is a common example of this.

Certain hydrogen bonds in the thermophile's proteins—meaning that the protein structure is more resistant to unfolding. The presence of certain types of salt has been observed to alter thermostability in the proteins, indicating that salt bridges likely also play a role in thermostability.[3] Other factors of protein thermostability are compactness of protein structure,[4] oligomerization,[5] and strength interaction between subunits.

Thermostable enzymes such as Taq polymerase and Pfu DNA polymerase are used in polymerase chain reactions where temperatures of 94 °C or over are used to melt apart DNA strands.[6]

Approaches to improve thermostability of proteins

Protein engineering can be used to enhance the thermostability of proteins. A number of site-directed and random mutagenesis techniques,[7][8] in addition to directed evolution,[9] have been used to increase the thermostability of target proteins. Comparative methods have been used to increase the stability of mesophilic proteins based on comparison to thermophilic homologs.[10][11][12][13] Additionally, analysis of the protein unfolding by molecular dynamics can be used to understand the process of unfolding and then design stabilizing mutations.[14] Rational protein engineering for increasing protein thermostability includes mutations which truncate loops, increase salt bridges[15] or hydrogen bonds, introduced disulfide bonds.[16] In addition, ligand binding can increase the stability of the protein, particularly when purified.[17]

Thermostable toxins

Certain poisonous fungi contain thermostable toxins, such as amatoxin found in the death cap and autumn skullcap mushrooms and patulin from molds. Therefore, applying heat to these will not remove the toxicity and is of particular concern for food safety.[18]

See also

Thermophiles

External links

  • Thermostability of Proteins

References

  1. ^ Takami, H; Takaki, Y; Chee, G. J.; Nishi, S; Shimamura, S; Suzuki, H; Matsui, S; Uchiyama, I (2004). "Thermoadaptation trait revealed by the genome sequence of thermophilic Geobacillus kaustophilus". Nucleic Acids Research 32 (21): 6292–303.  
  2. ^ Neves, C; Da Costa, M. S.; Santos, H (2005). "Compatible solutes of the hyperthermophile Palaeococcus ferrophilus: Osmoadaptation and thermoadaptation in the order thermococcales". Applied and Environmental Microbiology 71 (12): 8091–8.  
  3. ^ Das, R; Gerstein, M (2000). "The stability of thermophilic proteins: A study based on comprehensive genome comparison". Functional & Integrative Genomics 1 (1): 76–88.  
  4. ^ Thompson, M. J.; Eisenberg, D (1999). "Transproteomic evidence of a loop-deletion mechanism for enhancing protein thermostability". Journal of Molecular Biology 290 (2): 595–604.  
  5. ^ Tanaka, Y; Tsumoto, K; Yasutake, Y; Umetsu, M; Yao, M; Fukada, H; Tanaka, I; Kumagai, I (2004). "How oligomerization contributes to the thermostability of an archaeon protein. Protein L-isoaspartyl-O-methyltransferase from Sulfolobus tokodaii". Journal of Biological Chemistry 279 (31): 32957–67.  
  6. ^ Saiki, R. K.; Gelfand, D. H.; Stoffel, S; Scharf, S. J.; Higuchi, R; Horn, G. T.; Mullis, K. B.; Erlich, H. A. (1988). "Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase". Science 239 (4839): 487–91.  
  7. ^ Sarkar, C. A.; Dodevski, I; Kenig, M; Dudli, S; Mohr, A; Hermans, E; Plückthun, A (2008). "Directed evolution of a G protein-coupled receptor for expression, stability, and binding selectivity". Proceedings of the National Academy of Sciences 105 (39): 14808–13.  
  8. ^ Asial, I; Cheng, Y. X.; Engman, H; Dollhopf, M; Wu, B; Nordlund, P; Cornvik, T (2013). "Engineering protein thermostability using a generic activity-independent biophysical screen inside the cell". Nature Communications 4: 2901.  
  9. ^ Hoseki, J; Yano, T; Koyama, Y; Kuramitsu, S; Kagamiyama, H (1999). "Directed evolution of thermostable kanamycin-resistance gene: A convenient selection marker for Thermus thermophilus". Journal of biochemistry 126 (5): 951–6.  
  10. ^ Sayed, A; Ghazy, M. A.; Ferreira, A. J.; Setubal, J. C.; Chambergo, F. S.; Ouf, A; Adel, M; Dawe, A. S.; Archer, J. A.; Bajic, V. B.; Siam, R; El-Dorry, H (2014). "A novel mercuric reductase from the unique deep brine environment of Atlantis II in the Red Sea". Journal of Biological Chemistry 289 (3): 1675–87.  
  11. ^ Perl, D; Mueller, U; Heinemann, U; Schmid, F. X. (2000). "Two exposed amino acid residues confer thermostability on a cold shock protein". Nature Structural Biology 7 (5): 380–3.  
  12. ^ Lehmann, M; Pasamontes, L; Lassen, S. F.; Wyss, M (2000). "The consensus concept for thermostability engineering of proteins". Biochimica et biophysica acta 1543 (2): 408–415.  
  13. ^ Sauer, DB; Karpowich, NK; Song, JM; Wang, DN (6 October 2015). "Rapid Bioinformatic Identification of Thermostabilizing Mutations.". Biophysical journal 109 (7): 1420–8.  
  14. ^ Liu, H. L.; Wang, W. C. (2003). "Protein engineering to improve the thermostability of glucoamylase from Aspergillus awamori based on molecular dynamics simulations". Protein engineering 16 (1): 19–25.  
  15. ^ Lee, C. W.; Wang, H. J.; Hwang, J. K.; Tseng, C. P. (2014). "Protein thermal stability enhancement by designing salt bridges: A combined computational and experimental study". PloS one 9 (11): e112751.  
  16. ^ Mansfeld, J; Vriend, G; Dijkstra, B. W.; Veltman, O. R.; Van Den Burg, B; Venema, G; Ulbrich-Hofmann, R; Eijsink, V. G. (1997). "Extreme stabilization of a thermolysin-like protease by an engineered disulfide bond". The Journal of biological chemistry 272 (17): 11152–6.  
  17. ^ Mancusso, R; Karpowich, N. K.; Czyzewski, B. K.; Wang, D. N. (2011). "Simple screening method for improving membrane protein thermostability". Methods 55 (4): 324–9.  
  18. ^ "FDA: Moldy applesauce repackaged by school lunch supplier". NBC News. NBC News. Retrieved 15 April 2015. 
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