Interaction of High Density Lipoprotein with Nicotine – an IR and Raman Study

The direct interaction of high density lipoprotein (HDL) with nicotine, one of the major components of cigarette particulate matter, has been studied here at molecular level. Nicotine affects the vibration modes of HDL due to its embedment within the lipid monolayer. The changes in the positions and intensities of vibration bands in protein and lipid domain of the particle were studied by IR and Raman spectroscopy. Three types of samples were prepared: native HDL sample and two HDL samples with added nicotine. The molecular ratio of nicotine /phospholipids in two samples was 1 :12 and 1 :6. The same types of samples were prepared from liposomes containing phosphatidylcholine, and sphingomyelin with addition of cholesterol. Spectra of liposome samples were used for distinguishing and attribution of lipid bands in spectra of HDL samples, where the majority of changes were observed. The incorporation of nicotine into lipid monolayer induces changes in the lipid bands from the vibrations in acyl chains and head groups of phospholipids. The changes in vibration bands from particular amino acids' residues confirm that nicotine molecule is located within lipid monolayer but close to lipid-protein interface.