Water orientation and motion in phospholipid bilayers: a comparison between 17O- and 2H-NMR

A Solid State Multinuclear Magnetic Resonance Study of the Sol-Gel Process using Polysilicate Precursors

A solid state multinuclear NMR study of the sol-gel process was performed using the molecular building blocks tetramethoxysilane, hexamethoxydisiloxane, octamethoxytrisiloxane and octamethoxyoctasilsesquioxane as precursor monomers. Water content, solvent content, and hydrolysis/condensation processes were monitored using 17O, 13C, and 29Si FT, FTMAS and CPMAS NMR techniques.

Line shape analyses for water 17O NMR quintet observed in a bacteriophage Pf1 solution at different temperatures

Partially resolved 17O NMR quintet was observed in a filamentous bacteriophage Pf1 solution at 70 degrees C with a quadrupole splitting approximately 100 Hz. As the temperature decreased, the resolution was reduced but the line shapes were still indicative of residual quadrupole splitting. Line shape analyses were performed using the quadrupolar relaxation theory for spin 5/2. The contribution to the residual quadrupole splitting from the electric field gradients stemming from the phage filaments, which were oriented in the magnet, was taken into account. As a result, the observed 17O spectra at different temperatures were simulated and the hydration number of the phage DNA was determined.

Theoretical conformational analysis of phospholipids. II. Role of hydration in the gel to liquid crystal transition of phospholipids

To obtain a satisfactory agreement between computed transition temperatures and those determined experimentally, we introduce explicitly water molecules which hydrate the polar headgroup of dipalmitoylphosphatidylethanolamine molecules. The calculated free energy curves as a function of the intermolecular interchain distance and the degree of hydration of the polar groups permit the determination of the transition of the phospholipid system from the gel to the liquid crystalline phase. The detailed structure of the hydration shell is defined using the supermolecular approach.