INFLUENCE OF PH ON THE PRECURSORS OF PHOSPHOLIPID TUBULES IN METHANOLIC SOLUTION

Quasielastic light scattering measurements are reported for a 4 mg/ml solution of (10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine in an 8 5:15 (by vol.) methanol/water mixture as a function of temperature and pH. We find that the tubule-liposome phase transition temperature is relatively insensitive to pH, whereas the transition from liposome to the high temperature clear phase varies strongly and nonmonotonically with temperature. The hydrodynamic radius of the liposome was measured as a function of pH, temperature and time after cooling from the clea r phase. In addition, the average wall thickness of the liposomes is e stimated from sedimentation data and found to be considerably greater than that of the tubule.