A structural study of lamellar phases formed by nucleoside-functionalized lipids
We report a neutron-scattering investigation of lamellar phases formed by novel phospholipids bearing nucleosides at the polar-head-group region. These nucleolipids can interact through stacking and H-bond interactions, following a pattern that resembles base–base coupling in natural nucleic acids (DNA, RNA), i.e. they have similar recognition properties. Bilayer stacks formed of DPP–adenosine, DPP–uridine and their 1:1 mixture were investigated after equilibration in a 98% relative humidity atmosphere. The DPP–adenosine spectrum can be accounted for (in analogy to DPPC) by a lamellar phase with a smectic period of about 60 Å. DPP–uridine displays a not so straightforward behavior that we have tentatively ascribed to the coexistence of lamellae with different smectic periods. In the 1:1 mixture the lamellar mesophase of DPP–uridine is retained, suggesting a specific interaction of the uridine polar-head group with the adenosine moiety of DPP–adenosine. It should be stressed that this behavior can be considered as an indication of the recognition process occurring at the polar-head-group region of the mixed phospholiponucleoside membrane.