From: Robert Gilbert <gilbert@strubi.ox.ac.uk>
  To  : Helmut Coelfen <Helut.Coelfen@MPIKG-GOLM.MPG.DE>
  Date: Thu, 08 Mar 2001 13:33:38 +0000

Re: Estimate of the density of hydration water

The demonstration that hydration water has a greater density (estimated at 10% >)
was made by Svergun, Zaccai and colleagues. Their paper is

 Proc. Nat'l Acad. Sci. USA (1998) 95, 2267-2272.

This has subsequently been shown crystallographically also.

By neutrons: Acta Crystallogr. (1999) D55, 978-987
By X-rays: J. Mol. Biol. (1999) 289, 547-564

Another consideration is that the hydration layer around hydrophobic residues
exposed at the surface of the membrane is thought to form a cage structure 4-5
Angstroms from the protein surface. This is discussed in the crystal structure
papers above and also in Proc. Nat'l Acad. Sci. (1999) USA 96, 481-486

yours,

Robert Gilbert




Helmut Coelfen wrote:

> Hello out there,
>
> for a principal investigation, I'm interested in the structuration of water by
> polymers expressed in a density increase. We find huge differences in the
> overall solution density when certain synthetic polyelectrolytes are added;
> far
> higher than expected from the buoyancy increment of the polymer. From some
> of the
> last AUC conference talks I think to remember that it was observed that
> hydration
> water of proteins has a higher density than bulk water - probably an effect
> of its
> structuration in the contact area to the protein. Does anyone of you have a
> citeable
> Reference about this effect ?
>
> Thanks a lot in advance for any help you can give.
>
> Best wishes
>
> Helmut Cölfen
>
> _______________________________________________________________
> Dr. Helmut Cölfen
> Max-Planck-Institute of Colloids and Interfaces
> Colloid Chemistry
> Am Mühlenberg 2
> 14424 Potsdam
> Germany
>
> Tel: --49 331 567-9513
> Fax: --49 331 567-9502
> http://www.mpikg-golm.mpg.de/kc/coelfen/
> _______________________________________________________________