LONG-RANGE TILT ORIENTATIONAL ORDER IN PHOSPHOLIPID MONOLAYERS - A COMPARISON OF THE ORDER IN THE CONDENSED PHASES OF DIMYRISTOYLPHOSPHATIDYLETHANOLAMINE AND DIPALMITOYLPHOSPHATIDYLCHOLINE

The morphology of the condensed phase domains is very different in mon olayers of dimyristoylphosphatidylethanolamine (DMPE) and dipalmitoylp hosphatidylcholine (DPPC). In DMPE monolayers, only the inner structur e indicates the chirality, whereas in DPPC domains the chirality is al so reflected by the outer shape. Nevertheless, there are some common f eatures. The condensed phase domains of both lipids reflect the chiral ity of the molecules. The condensed phases of both monolayers exhibit long range orientational order. As well as lines at which the molecula r orientation jumps, continuous changes in the molecular orientation a re also observed, indicating a low elastic energy caused by these chan ges in orientation. The domains of both phospholipids fuse independent of the molecular orientation in the contacting domain parts. The big head group of the DPPC molecule effects not only the phase behaviour a nd the collapse, but also the domain shape.