Chaotropic activity explained

Chaotropicity describes the entropic disordering of lipid bilayers and other biomacromolecules which is caused by substances dissolved in water. According to the original usage^[1] and work carried out on cellular stress mechanisms and responses,^{[2] [3] [4]} chaotropic substances do not necessarily disorder the structure of water.^[5]

The chaotropic activities of solutes in the aqueous phase (e.g. ethanol, butanol, urea, MgCl₂, and phenol) have been quantified using an agar-gelation assay.^[6] Whereas chaotropicity was first applied to studies of ions, it is equally applicable to alcohols, aromatics, ion mixtures, and other solutes.^{[7] [8]} Furthermore, hydrophobic substances known to stress cellular systems (including benzene and toluene) can chaotropically disorder macromolecules and induce a chaotrope-stress response in microbial cells, even though they partition into the hydrophobic domains of macromolecular systems.^{[4] [9]}

See also

• Chaotropic agent
• Hofmeister series

Notes and References

1. Hamaguchi & Geiduschek. The Effect of Electrolytes on the Stability of the Deoxyribonucleate Helix. J. Am. Chem. Soc.. 1962. 84. 8. 1329–1338. 10.1021/ja00867a001.
2. Hallsworth, J.E.. Ethanol-induced water stress in yeast. Journal of Fermentation and Bioengineering. 1998. 85. 2. 125–137. 10.1016/S0922-338X(97)86756-6.
3. Hallsworth, J.E., Heim, S. and Timmis, K.. Chaotropic solutes cause water stress in Pseudomonas putida. Environmental Microbiology. 2003. 5. 12. 1270–1280. 10.1111/j.1462-2920.2003.00478.x. 14641573.
4. Bhaganna, P.. Hydrophobic substances induce water stress in microbial cells. Microbial Biotechnology. 2010. 3. 6. 701–716. 10.1111/j.1751-7915.2010.00203.x. etal. 21255365. 3815343.
5. Ball, P. . Hallsworth, J.E.. Water structure and chaotropicity: their uses, abuses and biological implications . Physical Chemistry Chemical Physics. 2015. 17. 13. 8297–8305. 10.1039/C4CP04564E. 25628033. 2015PCCP...17.8297B.
6. Cray, J.A.. A universal measure of chaotropicity and kosmotropicity.. Environmental Microbiology. 2013. 15. 1. 287–296. 10.1111/1462-2920.12018. etal. 23145833.
7. Hallsworth, J.E.. Limits of life in MgCl₂-containing environments: chaotropicity defines the window.. Environmental Microbiology. 2007. 9. 3. 801–813. 10.1111/j.1462-2920.2006.01212.x. etal. 17298378.
8. Alves, F.L.. Concomitant osmotic and chaotropicity-induced stresses in Aspergillus wentii: compatible solutes determine the biotic window.. Current Genetics. 2015. 61. 3. 457–477. 10.1007/s00294-015-0496-8. 26055444. 14826577. etal.
9. Cray, J.A.. Chaotropicity: a key factor in product tolerance of biofuel-producing microorganisms.. Current Opinion in Biotechnology. 2015. 33. 228–259. 10.1016/j.copbio.2015.02.010 . 25841213. etal.