Molecular details of melittin-induced lysis of phospholipid membranes as revealed by deuterium and phosphorus NMR

摘要: Solid-state deuterium and phosphorus-31 nuclear magnetic resonance (/sup 2/H /sup 31/P NMR) studies of deuterium-enriched phosphatidylcholine (( 3',3'-/sup 2/H2)DPPC, (sn-2-/sup 2/H31)DPPC) ditetradecylphosphatidylglycerol (DMPG-diether), as water dispersions, were undertaken to investigate the action melittin on zwitterionic negatively charged membrane phospholipids. When lipid-to-protein ratio (Ri) is greater than or equal 20, 2H NMR spectral features indicate that system constituted by large bilayer structures several thousand angstrom curvature radius, at T Tc (Tc, temperature gel-to-liquid crystal phase transition pure lipid dispersions). At approximately Tc, a detailed analysis chain ordering shows induces slight disordering plateau positions concomitantly with substantial near center. much an apparent general observed. These findings suggest in contact acyl segments its position within may depend temperature. On cooling down below for Ri two-phase spectra are observed, i.e., narrow single resonances superimposed gel-type phosphorus powder patterns. characteristic ofmore » small (vesicles, micelles, ... few hundred radius) undergoing fast isotropic reorientation, which averages zero both quadrupolar chemical shift anisotropy interactions. increase above returns reversibly structures.« less