文摘
Terpenoids have an essential function in present-day cellular membranes, either as membrane reinforcers in Eucarya and Bacteria or as principal membrane constituents in Archaea. We have shown that some terpenoids, such as cholesterol and 伪, 蠅-dipolar carotenoids reinforce lipid membranes by measuring the water permeability of unilamellar vesicles. It was possible to arrange the known membrane terpenoids in a 鈥榩hylogenetic鈥?sequence, and a retrograde analysis led us to conceive that single-chain polyprenyl phosphates might have been 鈥榩rimitive鈥?membrane constituents. By using an optical microscopy, we have observed that polyprenyl phosphates containing 15 to 30 C-atoms form giant vesicles in water in a wide pH range. The addition of 10聽% molar of some polyprenols to polyprenyl phosphate vesicles have been shown to reduce the water permeability of membranes even more efficiently than the equimolecular addition of cholesterol. A 鈥榩rebiotic鈥?synthesis of C10 and C15 prenols from C5 monoprenols was achieved in the presence of a montmorillonite clay. Hypothetical pathway from C1 or C2 units to 鈥榩rimitive鈥?membranes and that from 鈥榩rimitive鈥?membranes to archaeal lipids are presented.