Probing the structure of water around biological molecules: concepts, constructs and consequences

Considerable progress is being made using neutron diffraction, combined with isotope substitution and computer simulation techniques, in understanding how water is organised around ions and molecules in solution. The variation of the structure of pure water with temperature and particularly with pressure gives important clues as to how solutes behave when in contact with water. It also helps to explain why it is some solutes dissolve readily in water while others resist dissolution, and why solution equilibria can be modified by subtle changes in the ionic and non-ionic composition of the solution. This paper describes how neutron scattering is applied to these problems and gives some examples of recent data and their interpretation. These results have wider ramifications in the fields of solution chemistry and hydration in biology. (C) 2000 Elsevier Science B.V. All rights reserved.