Spatial modulation of water ordering in lecithin bilayers. Evidence for a ripple-ripple phase transition.

摘要: Intense motional averaging effects on the 2H nuclear magnetic resonance (NMR) spectrum of 2H2O that occur in aqueous dispersions dimyristoyl-sn-glycero-3-phosphocholine (Myr2-PtdCho) are explained by a spatial modulation orientational order water induced ripplelike structures. The ratio amplitude to periodic length ripples, A/lambda, at molar water/Myr2-PtdCho 9.5:1, is measured NMR and found be consistent with x-ray measurements this P beta phase dipalmitoyl-sn-glycero-3-phosphocholine (Pam2-PtdCho) bilayers. sensitivity allows us report presence two distinct ripple phases mediated discontinuous change value A/lambda. This result suggests structures observed for several phospholipid systems excess freeze-fracture electron microscopy may associated different instead same as previously assumed.