A Raman spectroscopic study of the effect of hydrocarbon chain length and chain unsaturation on lecithin‐cholesterol interaction

The effect of cholesterol in equimolar concentrations on five different types of phospholipids in aqueous systems is reported. The phospholipids varied in chain length and chain unsaturation. This investigation confirms that the CH stretching region at 2700–3100 cm −1 is sensitive to conformational changes in the hydrocarbon chains. Moreover, this region of the Raman spectrum shows that small changes in band intensities can be correlated with the effect of the cholesterol on aqueous lecithin system both above and below the chain transition temperature ( T c ). The results indicate that cholesterol moderates the change in chain mobility in both directions of the transition liquid crystal⇌gel phase. This effect is larger in lecithins with saturated chains compared to unsaturated chains.