DI(POLYPRENYL) PHOSPHATES AS MODELS FOR PRIMITIVE MEMBRANE CONSTITUENTS - SYNTHESIS AND PHASE PROPERTIES

Identical- and mixed-chain di(polyprenyl) phosphates derived from 3-me thyl-2-buten-1-ol, (E)-geraniol, (E,E)-farnesol. (E,E,E)-geranylgerani ol, (R)-citronellol, or (R)-tetrahydrogeraniol have been synthesized b y phosphitylation and oxidation with iodine/water. These phosphates ga ve organized systems in water, in particular vesicles, the physical pr operties of which were studied by photon correlation spectroscopy, ele ctron microscopy, entrapment of a fluorescent dye (calcein), P-31 NMR, stopped-flow/light-scattering studies, and fluorescence polarization with lipophilic probes. Interdigitation of mixed-length phosphates was not found to have any favorable effect on the stability of the vesicl es. The C->15 vesicles were formed despite the fact that they are comp osed of only one molecular species and are devoid of any reinforcer, b ut those with two geranyl chains appeared to be rather fragile. Phosph ates containing C-5 chains are soluble in water. The results obtained lend weight to the hypothesis that polyprenyl phosphates might have be en primitive membrane constituents, and stimulate the search for appro priate reinforcers.