Analysis of superhelical structures of nucleic acid-lipid conjugates by image processing.

Nucleoside-phospholipid conjugates containing a nucleotidyl residue and two long alkyl chains have been synthesized and their self-organization and morphology have been investigated. In particular, 5'-phosphatidylcytidine spontaneously assembled to form linear and circular strands. Image processing analysis of the electron micrograph of the strands confirmed that they are indeed double helix reminiscent of the double-helical structure of nucleic acids. The linear and circular strands from 5'-phosphatidylcytidine had grooves of approximately 100 A in diameter and right-handed helical pitch of approximately 240 A.