The role of chain rigidity in lipid self-association: comparative study of dihexanoyl- and disorbyl-phosphatidylcholines

In the course of structure–function investigations of lipids a phosphatidylcholine molecule with short and rigid tails, di-2,4-hexadienoylphosphatidylcholine (DiSorbPC), was synthesized and studied in comparison with its saturated analog, dihexanoylphosphatidylcholine (DHPC). Conjugated double bonds in the acyl chains in DiSorbPC reduce considerably the number of possible conformers of the lipid within an aggregate. This leads to impaired packing of unsaturated acyl chains and thus, to a surprisingly high (115 Å²) area per molecule for DiSorbPC at the air–water interface and failure to form micelles of regular size and shape. Details on DiSorbPC aggregation and packing provided by a set of experimental techniques combined with molecular dynamics simulations are presented.