Sheeza Khan, Faizan Ahmad
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi – 110025, India.
In organisms, living in arid environments, water conservation is associated with the production of concentrated, hyperosmolar urine. The countercurrent system in which this concentration takes place is beneficial for the whole organism but this requires specific mechanisms for the urea accumulating cells to cope with the extreme and sometimes rapid fluctuations in osmolality of the extracellular space. A mechanism of adaptation that protects the cellular components against these denaturing stresses involves the accumulation of small organic molecules known as osmolytes. Many landmark discoveries have uncovered the osmolyte-induced protein folding and stabilization. Many organisms use mixtures of osmolyte types; e.g., the mammalian kidney along with urea, contains the polyols- myo-inositol and sorbitol, certain methylamines and taurine. We have investigated the effect of the nonmethylamine osmolytes in counteracting the effects of urea on protein stability. Our thermodynamic measurements (Tm and ΔG D 0 ) on different proteins led us to conclude that nonmethylamines have a significant effect on protein stability of urea rich cells. Read more…