Osmolyte

Osmolytes are compounds affecting osmosis.[1] They are soluble in the solution within a cell, or in the surrounding fluid, e.g. as plasma osmolytes. They play a role in maintaining cell volume and fluid balance. For example, when a cell swells due to external osmotic pressure, membrane channels open and allow efflux of osmolytes which carry water with them, restoring normal cell volume.[2] Osmolytes also contribute to protein folding.[3] Natural osmolytes that can act as osmoprotectants include trimethylamine N-oxide (TMAO), dimethylsulfoniopropionate, sarcosine, betaine, glycerophosphorylcholine, myo-inositol, taurine, glycine, and others.[4][5] Remarkably, TMAO has the capacity to restore glucocorticoid binding to mutant receptors.[6] Bacteria accumulate osmolytes for protection against a high osmotic environment.[7] The osmolytes will be neutral non-electrolytes, except in bacteria that can tolerate salts.[5] In humans, osmolytes are of particular importance in the renal medulla.[8] Current understanding of osmolytes have been used to calculate the maximum depth where a fish can survive: 26,900 feet (8,200 meters).[9]

References

  1. ↑ "everythingbio.com".
  2. ↑ Review of Medical Physiology, William F. Ganong, McGraw-Hill Medical, ISBN 978-0-07-144040-0.
  3. ↑ Bolen DW, Baskakov IV (2001). "The osmophobic effect: natural selection of a thermodynamic force in protein folding". Journal of Molecular Biology. 310 (5): 955–963. doi:10.1006/jmbi.2001.4819. PMID 11502004.
  4. ↑ Neuhofer, W.; Beck, F. X. (2006). "Survival in Hostile Environments: Strategies of Renal Medullary Cells". Physiology. 21 (3): 171–180. doi:10.1152/physiol.00003.2006. PMID 16714475.
  5. 1 2 Arakawa T, Timasheff SN (1985). "The stabilization of proteins by osmolytes". Biophysical Journal. 47 (3): 411–414. Bibcode:1985BpJ....47..411A. doi:10.1016/s0006-3495(85)83932-1. PMC 1435219. PMID 3978211.
  6. ↑ Miller, AL; Elam, WA; Johnson, BH; Khan, SH; Kumar, R; Thompson, EB (2017). "Restored mutant receptor:Corticoid binding in chaperone complexes by trimethylamine N-oxide". PLOS One. 12 (3): e0174183. doi:10.1371/journal.pone.0174183. PMC 5354453. PMID 28301576.
  7. ↑ Csonka LN (1989). "Physiological and genetic responses of bacteria to osmotic stress". Microbiology and Molecular Biology Reviews. 53 (1): 121–147. PMC 372720. PMID 2651863.
  8. ↑ Gallazzini, M.; Burg, M. B. (2009). "What's New About Osmotic Regulation of Glycerophosphocholine". Physiology. 24 (4): 245–249. doi:10.1152/physiol.00009.2009. PMC 2943332. PMID 19675355.
  9. ↑ Yancey PH, Gerringer ME, Drazen JC, Rowden AA, Jamieson A (2014). "Marine fish may be biochemically constrained from inhabiting the deepest ocean depths". PNAS. 111 (12): 4461–4465. Bibcode:2014PNAS..111.4461Y. doi:10.1073/pnas.1322003111. PMC 3970477. PMID 24591588.

Further reading

  • Rose GD, Fleming PJ, Banavar JR, Maritan A (November 2006). "A backbone-based theory of protein folding". Proc. Natl. Acad. Sci. U.S.A. 103 (45): 16623–33. Bibcode:2006PNAS..10316623R. doi:10.1073/pnas.0606843103. PMC 1636505. PMID 17075053.
  • Yancey PH (August 2005). "Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses". J. Exp. Biol. 208 (Pt 15): 2819–30. doi:10.1242/jeb.01730. PMID 16043587.
  • Holthauzen LM, Bolen DW (February 2007). "Mixed osmolytes: the degree to which one osmolyte affects the protein stabilizing ability of another". Protein Sci. 16 (2): 293–8. doi:10.1110/ps.062610407. PMC 2203298. PMID 17189473.
  • Harries, Daniel; Rösgen, Jörg (2008). "A Practical Guide on How Osmolytes Modulate Macromolecular Properties". Meth. Cell Bio. 84: 679–735. doi:10.1016/S0091-679X(07)84022-2.
  • Hochachka, P.W.; Somero, G. N (2002). "Biochemical Adaptation. Mechanism and Process in Physiological Evolution". Oxford: Oxford University Press.


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