Characterization of the phase behavior of phosphonolipids in model and biological membranes by 31P-NMR

Abstract

31P-NMR is used to characterize the phase behavior of phosphonolipids in both model and biological membranes. ( 1′,2′- Dipalmitoyl-sn- glyceryl)-2-aminoethylphosphonate gives rise to static chemical shift tensor elements (−87, 5 and 63 ppm) which differ considerably from those reported for the analogous phospholipid, 1,2- dipalmitoyl-sn- glycero-3-phosphoethanolamine (−81, −20 and 105 ppm). Phosphonolipid, as well as a mixture of phosphonolipid and 1,2- dipalmitoyl-sn- glycero-3-phosphocholine , in aqueous dispersion gives rise to 31P spectra which may be interpreted in terms of lamellar structures. A mixture of phosphonolipid and egg phosphatidylethanolamine exhibits a bilayer-to-hexagonal phase transition with a concomitant decrease by one-half in the value of the 31P chemical shift anisotropies of both the phosphonate and phosphate resonances. The chemical shift anisotropy associated with phosphonolipid has been found to be consistently smaller than that observed for the analogous phospholipid. 31P-NMR spectra of total lipid extracts of Tetrahymena sp. indicate that both phospho- and phosphonolipids have a bilayer organization between −20 and 20°C.