THE STRUCTURE OF ANHYDROUS AND HYDRATED DIMYRISTOYLPHOSPHATIDYL GLYCEROL - A PRESSURE TUNING INFRARED SPECTROSCOPIC STUDY

The addition of water to anhydrous phospholipids has profound effects on the intermolecular interactions and packing order of phospholipid molecules- These changes, as well as alterations induced by hydration in the orientation of the acyl chains, can be qualitatively assessed using high pressure infrared spectroscopy. Application of this technique to dimyristoylphosphatidyl glycerol (DMPG) showed that hydration causes major changes in (i) the orientation of the carboxyl groups in relation to the glycerol backbone; (ii) the degree of orientational disorder of the acyl chains and (iii) the proximity of neighbouring DMPG molecules. In addition, the frequency of the carbonyl group is shown to be strongly affected not only by changes in the hydrogen bond network, but also by subtle environmental perturbations induced by the conformation of nearby structural units.