13C nuclear magnetic resonance relaxation studies on the structure of mixed micelles of the nonionic surfactant triton X-100 and phospholipids

Abstract

Natural abundance 13C nuclear magnetic resonance studies on dimyristoyl phosphatidylcholine in CD 3OD and on dimyristoyl and dipalmitoyl phosphatidylcholine in mixed micelles with the nonionic surfactant Triton X-100 are reported. In the 13C nuclear magnetic resonance spectrum of mixed micelles, resolution of several individual phospholipid resonance lines is possible. The phospholipid shows similar T 1 values to phospholipid in unsonicated multibilayer and sonicated vesicle structures, and presumably similar segmental motions of the phospholipid fatty acid chains occur in all of these systems. The phospholipid in mixed micelles, however, appears to exhibit narrower lines and longer T 2 ∗ relaxation times than it does in the bilayer preparations and this suggests that less motional restrictions occur for phospholipids in mixed micellar structures than in bilayer structures.