Archaebacterial lipids: highly proton-impermeable membranes from 1,2-diphytanyl-sn-glycero-3-phosphocholine

Unlike ordinary glycero-lipids such as egg-yolk lecithin, 1,2-diphytanyl-sn-glycero-3-phosphocholine, which was employed as a model lipid of archaebacterial acidophiles, gave liposomal membranes which were highly resistant to proton permeation in a wide temperature range (about 10-50 degrees C); the permeability coefficient and activation energy of the flux were 0.7 x 10(-5) cm/s at 20 degrees C and 24.5 kcal/mol, respectively. The high resistance to proton flow was attributed to a fluid and bulky isoprenoid chain-layer of the membrane.