We report on spectroscopic studies of the chiral structure in phospholipid tubules formed in mixtures of alcohol and water. Synthetic phospholipids containing di- acetylenic moieties in the acyl chains self-assemble into hol- low, cylindrical tubules in appropriate conditions. Circular dichroism provides a direct measure of chirality of the mo- lecular structure. We find that the CD spectra of tubules formed in mixtures of alcohol and water depends strongly on the alcohol used and the lipid concentration. The relative spectral intensity of different circular dichroism bands cor- relates with the number of bilayers observed using micros- copy. The results provide experimental evidence that tubule formation is based on chiral packing of the lipid molecules and that interbilayer interactions are important to the tubule structure.
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