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Old 05-10-2011, 12:35 PM   #2560
alkemical
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http://www.astrobio.net/pressrelease...ter-shapes-dna

How Water Shapes DNA

Water molecules surround the genetic material DNA in a very specific way. Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have discovered that, on the one hand, the texture of this hydration shell depends on the water content and, on the other hand, actually influences the structure of the genetic substance itself. These findings are not only important in understanding the biological function of DNA; they could also be used for the construction of new DNA-based materials.

The DNA's double helix never occurs in isolation; instead, its entire surface is always covered by water molecules which attach themselves with the help of hydrogen bonds. But the DNA does not bind all molecules the same way.

"We've been able to verify that some of the water is bound stronger whereas other molecules are less so," notes Dr. Karim Fahmy, Head of the Biophysics Division at the Institute of Radiochemistry. This is, however, only true if the water content is low. When the water sheath swells, these differences are adjusted and all hydrogen bonds become equally strong. This, in turn, changes the geometry of the DNA strand: The backbone of the double helix, which consists of sugar and phosphate groups, bends slightly. "The precise DNA structure depends on the specific amount of water surrounding the molecule," summarizes Dr. Fahmy.


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