X-Ray Study of Model Systems: Structure of the Lipid-Water Phases in Correlation with the Chemical Composition of the Lipids

One of the characteristic properties of lipids is to display a variety of phases, in the presence of water, by the interplay of parameters (temperature, water concentration, lipid composition) that often remain within the range of physiological conditions (see review in reference 1). We wish to summarize here some of the major properties of the lipid-water systems, to report experiments (many of which are still unpublished) aimed at investigating the influence of the composition of the lipids on the structure of the various phases, and finally to envisage the possible biological significance of those observations.