Structural and morphological transition of long-chain phospholipid vesicles induced by mixing with short-chain phospholipid.

Effects of a short-chain phospholipid, dihexanoylphosphatidylcholine (DHPC), on the structure and morphology of membrane assemblies of a long-chain phospholipid, dimyristoylphosphatidylcholine (DMPC), were examined by fluorescence spectroscopy, differential scanning calorimetry (DSC), and cryogenic transmission electron microscopy (cryo-TEM). It was found by fluorescence measurements that DHPC affects on the gel and liquid crystalline state of DMPC vesicle membranes in different ways. Further, the result of DSC suggested that, along the transition process from DMPC vesicle to DMPC-DHPC mixed micelle, there are at least three different concentration regions which are characterized by the individual variation pattern of the transition temperature and enthalpy change.