Osmolyte

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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 contributes to protein folding.[3]

Natural osmolytes that can act as osmoprotectants include trimethylamine N-oxide (TMAO), dimethylsulfoniopropionate, trimethylglycine, sarcosine, betaine, glycerophosphorylcholine, myo-inositol, taurine, glycine, and others.[4][5] Bacteria accumulate osmolytes for protection against a high osmotic environment.[6] 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.[7] Current understanding of osmolytes have been used to calculate the maximum depth where a fish can survive at 26,900 feet (8,200 meters).[8]

References[edit]

  1. ^ everythingbio.com
  2. ^ Review of Medical Physiology, William F. Ganong, McGraw-Hill Medical, ISBN 978-0-07-144040-0.
  3. ^ Bolen DW1, Baskakov IV (2001). "The osmophobic effect: natural selection of a thermodynamic force in protein folding". Journal of Molecular Biology 310 (5): 955–963. 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.  edit
  5. ^ a b Arakawa T, Timasheff SN (1985). "The stabilization of proteins by osmolytes". Biophysical Journal 47 (3): 411–414. PMC 1435219. PMID 3978211. 
  6. ^ 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. 
  7. ^ 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.  edit
  8. ^ http://www.pnas.org/content/111/12/4461/

Further reading[edit]

  • Hochachka, P.W.; Somero, G. N (2002). "Biochemical Adaptation. Mechanism and Process in Physiological Evolution". Oxford: Oxford University Press.