Properties of ω-cyclohexane fatty acids in membranes

AbstractThe properties of di-ω-cyclohexyldodecanoylphosphatidylcholine (DCDPC) in various model membranes were studied by differential scanning calorimetry (DSC) and the monolayer technique. DCDPC shows a broad phase transition at 13°C with a total enthalpy of 4.1 kcalmol as measured by DSC. In a DCDPC monolayer no phase transition was observed. At 25 dyncm the area increases linearly with temperature. The molecular area at 40°C and 25 dyncm equals that of dipalmitoylphosphatidylcholine. DCDPC liposome experiments show that the permeability of glycerol is strongly reduced above the phase transition in comparison with linear saturated fatty acid-containing phosphatidylcholines of comparable chain lengths. These results suggest that lipids with ω-cyclohexane fatty acids may possess a high acyl chain density at the free fatty acid end in the core of the membrane, which stabilizes the membrane and influences the permeability. This seems to be an important mechanism for membrane adaptation under various conditions for thermoacidophilic bacteria