Relationship between molecular structure and supramolecular morphology of DODA-EO2-biotin and related lipids

Abstract

We have recently reported that a biotinylated lipid molecule, called DODA-EO2-biotin, forms tubular lipid structures upon hydration, which act as a matrix for the formation of ordered helical arrays of streptavidin as well as for secondary macromolecular recognition reactions involving biotinylated structures (Ringler et al., 1997). In the present study, the supramolecular structures formed by the compounds obtained during the synthesis of DODA-EO2-biotin and of compounds structurally related to DODA-EO2-biotin were investigated by transmission electron microscopy, with the objective being to understand the relationship between molecular structure and supramolecular morphology. From the eight lipid molecules investigated, only DODA-EO2-biotin formed tubular structures. Several structural parameters were identified as playing a role in the formation of DODA-EO2-biotin tubes, such as the chirality of the biotin moiety, the saturated nature of the lipid chains, the presence of amide bonds and the correct length and structure of the hydrophilic spacer. In addition, helical crystals of streptavidin were only obtained upon binding of streptavidin to the supramolecular assemblies formed by DODA-EO2-biotin.