Denaturation (biochemistry)

The effects of temperature on enzyme activity.
Top: increasing temperature increases the rate of reaction (Q10 coefficient).
Middle: the fraction of folded and functional enzyme decreases above its denaturation temperature.
Bottom: consequently, an enzyme's optimal rate of reaction is at an intermediate temperature.
IUPAC definition

Process of partial or total alteration of the native secondary, and/or tertiary, and/or quaternary structures of proteins or nucleic acids resulting in a loss of bioactivity.

Note 1: Modified from the definition given in ref.[1]

Note 2: Denaturation can occur when proteins and nucleic acids are subjected to elevated temperature or to extremes of pH, or to nonphysiological concentrations of salt, organic solvents, urea, or other chemical agents.

Note 3: An enzyme loses its ability to alter or speed up a chemical reaction when it is denaturized.[2]

In biochemistry, denaturation is a process in which proteins or nucleic acids lose folded structure present in their native state due to various factors, including application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent (e.g., alcohol or chloroform), agitation and radiation, or heat.[3] If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. Protein denaturation is also a consequence of cell death.[4][5] Denatured proteins can exhibit a wide range of characteristics, from conformational change and loss of solubility or dissociation of cofactors to aggregation due to the exposure of hydrophobic groups. The loss of solubility as a result of denaturation is called coagulation.[6] Denatured proteins lose their 3D structure, and therefore, cannot function.

Proper protein folding is key to whether a globular or membrane protein can do its job correctly; it must be folded into the native shape to function. However, hydrogen bonds and cofactor-protein binding, which play a crucial role in folding, are rather weak, and thus, easily affected by heat, acidity, varying salt concentrations, chelating agents, and other stressors which can denature the protein. This is one reason why cellular homeostasis is physiologically necessary in most life forms.

  1. ^ Alan D. MacNaught; Andrew R. Wilkinson, eds. (1997). Compendium of Chemical Terminology: IUPAC Recommendations (the "Gold Book"). Blackwell Science. ISBN 978-0865426849.
  2. ^ Vert, Michel (2012). "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)" (PDF). Pure and Applied Chemistry. 84 (2): 377–410. doi:10.1351/PAC-REC-10-12-04. S2CID 98107080. Archived (PDF) from the original on 2013-09-27.
  3. ^ Mosby's Medical Dictionary (8th ed.). Elsevier. 2009. Retrieved 1 October 2013.
  4. ^ Samson, Andre L.; Ho, Bosco; Au, Amanda E.; Schoenwaelder, Simone M.; Smyth, Mark J.; Bottomley, Stephen P.; Kleifeld, Oded; Medcalf, Robert L. (2016-11-01). "Physicochemical properties that control protein aggregation also determine whether a protein is retained or released from necrotic cells". Open Biology. 6 (11): 160098. doi:10.1098/rsob.160098. ISSN 2046-2441. PMC 5133435. PMID 27810968.
  5. ^ Samson, Andre L.; Knaupp, Anja S.; Sashindranath, Maithili; Borg, Rachael J.; Au, Amanda E.-L.; Cops, Elisa J.; Saunders, Helen M.; Cody, Stephen H.; McLean, Catriona A. (2012-10-25). "Nucleocytoplasmic coagulation: an injury-induced aggregation event that disulfide crosslinks proteins and facilitates their removal by plasmin". Cell Reports. 2 (4): 889–901. doi:10.1016/j.celrep.2012.08.026. ISSN 2211-1247. PMID 23041318.
  6. ^ "2.5: Denaturation of proteins". Chemistry LibreTexts. 2019-07-15. Retrieved 2022-04-25.