On the propensity of phosphatidylglycerols to form interdigitated phases.

ABSTRACT: We have determined the phase behavior of disaturated phosphatidylglycerols (PGs) of chain lengths n(CH2) = 14-18 at high pH and ionic strength using calorimetry, dilatometry, as well as x-ray diffraction. PGs with n(CH2) = 14 and 16 show thermotropic behavior similar to that of phosphatidylcholines (PCs). The area/lipid obtained in the gel phase is smaller than that reported for PCs despite the expected larger effective headgroup size. This can be explained by the tilting of the PG headgroup out of the bilayer plane, and we provide experimental evidence for a headgroup tilt transition. For distearoyl PG, we further find that the "usual" gel phase coexists with an interdigitated phase, which exhibits a transition from an orthorhombic into a hexagonal chain packing. The total amount of the i

SUBMITTER: Pabst G 

PROVIDER: S-EPMC1896241 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature