Objectif All biological membranes consist of a lipid bilayer within which a wide range of proteins is embedded. The lipid bilayer is the basic structural framework for the activity of the proteins; hence an accurate understanding of its structure is essential for molecular biology. There are two common states of mobility for the lipids. The first is an almost fully molten state similar to that of liquid hydrocarbons, the second, known as the gel phase (Lb), has mobility similar to that of hydrocarbon "rotator" phases. In model systems at equilibrium these two states occur as separate phases. In natural membrane systems the presence of gel and lamellar states within a single membrane is well established, although the presence of the gel is not an optimum condition for cell growth. In this study we will examine three major objectives to elucidate the detailed behaviour and structure of gel/lamellar coexistence. First, whether or not the coexistence of the two states can be induced in single bilayers in specially selected model phospholipid systems (lecithins) will be investigated. Secondly, the detailed structures of the alkyl chains in the various gel phases will be examined. Thirdly, gel and lamellar coexistence in natural lipid extracts will be studied.The project is multi-disciplinary, involving thermal analysis (DSC.DTA) polarising optical and electron microscopy, laboratory and synchrotron Xray studies, multi-nuclear NMR, and neutron scattering. The range of experimental techniques has been selected to measure both macroscopic and molecular properties in order to address these problems. It is timely to undertake this project now because recent developments in the techniques have much improved their measurement capability, whilst the general background information about lipid/surfactant mesophases has also advanced significantly.This work will lead to a significant increase in the understanding of the structure of biomembranes. The presence of gel patches in natural membranes has obvious implications for membrane function. The gel patches will influence diffusion across and within the membrane. They will exclude some components, hence increasing their concentration elsewhere. This could lead to channel formation or to membrane fusion. It will certainly influence proteins on the surface and within the membranes, leading to changes in enzyme activity.As well as biological applications, there are many implications for pharmaceuticals, cosmetics/personal care products, foods and fabric care products. The market for gel phases is of order 105-6 tonnes p.a. with a value of at least £108-9 per year. Gel phases are employed as stabilisers in skin creams, as hair and fabric conditioners, and as slow release systems for drugs. A major new application is in the manufacture of low fat food products such as frozen deserts ("low fat ice creams") and spreads. With a sound understanding of gel phase structures in mixed chain lipids it will be possible to improve current products and to find novel applications, particularly in the areas of slow and controlled release. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) 4 - Life Sciences INTAS - INTAS Appel à propositions Data not available Régime de financement Data not available Coordinateur University of Manchester Contribution de l’UE Aucune donnée Adresse Sackville Street M60 1QD Manchester Royaume-Uni Voir sur la carte Coût total Aucune donnée Participants (4) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Russian Academy of Sciences Russie Contribution de l’UE Aucune donnée Adresse Tikhoretsky pr. 4 192212 St. Petersburg Voir sur la carte Coût total Aucune donnée St. Petersburg State University Russie Contribution de l’UE Aucune donnée Adresse Universitetskaya nab. 7/9 199034 St. Petersburg Voir sur la carte Coût total Aucune donnée St. Petersburg State University Russie Contribution de l’UE Aucune donnée Adresse Universitetski pr. 2 198904 St. Petersburg Voir sur la carte Coût total Aucune donnée University of Umea Suède Contribution de l’UE Aucune donnée Adresse 901 87 Umea Voir sur la carte Coût total Aucune donnée
