Dm. Czajkowsky et al., RIPPLE PHASE IN ASYMMETRIC UNILAMELLAR BILAYERS WITH SATURATED AND UNSATURATED PHOSPHOLIPIDS, Biochemistry, 34(39), 1995, pp. 12501-12505
In a solution of phosphate-buffered saline (PBS), unilamellar bilayers
with saturated phosphatidylcholines in one leaflet and negatively cha
rged, unsaturated phospholipids in the other leaflet were observed in
the ripple phase at room temperature using atomic force microscopy (AF
M). This is the first observation of the ripple phase in asymmetric bi
layers. Sodium and phosphate, components of PBS, were found to be nece
ssary for the formation of the ripple structure in the asymmetric bila
yers composed of dipalmitoylphosphatitdylcholine (DPPC) and 1-palmitoy
l-2-oleoylphosphatidyglycerol (POPG), demonstrating a dependency for s
pecific ions for this phase. These results indicate that the two leafl
ets of a bilayer are closely coupled to give rise to such a long range
and complicated morphology.