DIVERSITY IN THE FATTY-ACID CONFORMATION AND CHAIN PACKING OF CIS-UNSATURATED LIPIDS

Recent X-ray diffraction and Fourier transform IR spectroscopic studie s have unveiled a great diversity in the molecular conformation and ch ain packing of lipid molecules containing cis-unsaturated fatty-acid c hains. Specifically, a dramatic diversity in the olefinic conformation , subcell packing and chain-chain interactions has been clearly reveal ed by crystal structures of principal cis-monounsaturated fatty acids. The structural diversity is most manifest in oleic acid crystals. The se findings were applied to analyses of the complicated structural tra nsformations oi diacylglycerols and triacylglycerols containing oleic acid and saturated acid moieties, in which the stabilization oi the ol eic acid causes the complexity of the transformation and mixing behavi or. Although this knowledge has been obtained in the crystalline state , one may assume that the structural diversity of these unsaturated mo lecules plays a similar role in the lipids of biomembranes, lipoprotei ns and lipid deposits in which aliphatic chain packing is a critical p roblem, since some lipid domains can undergo liquid to solid or solid to liquid alterations.