Ripple phase formation in phosphatidylcholine: Effect of acyl chain relative length, position, and unsaturation

摘要: The ripple phases of a range mixed-acid phosphatidylcholine derivatives with one saturated C18 chain and the other variable length or unsaturation were studied using differential scanning calorimetry, x-ray diffraction, freeze-fracture electron microscopy. temperature dependences their wavelength ~l!, stacking repeat distance ( ds), monoclinic angle u m defining unit cell measured found to be consistent an inherently asymmetric phase amplitude that slowly increases temperature. spans mixed-chain containing unsaturated chains larger smaller, respectively, than those homoacyl same equivalent length. This was shown slidingchain model proposed by Cevc ~Biochemistry 30, 7186‐7197, 1991!. tendency form possible molecular organization such are discussed in terms different models. X-ray diffraction evidence for existence secondary about 1.8 times greater conventional pretransition phase. is formed samples freshly cooled from liquid-crystal tends persist longer on cooling gel Freeze-fracture microscopy suggests it symmetric cross section possibly reflecting interaction two opposing ripples. @S1063-651X~98!12209-2#