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Age and regional structural characterization of lipid hydrocarbon chains from human lenses by infrared, and near‐infrared raman, spectroscopies

1996; Wiley; Volume: 2; Issue: 2 Linguagem: Inglês

10.1002/(sici)1520-6343(1996)2

1520-6343

Douglas Borchman, Yukihiro Ozaki, Om P. Lamba, William Craig Byrdwell, Marta C. Yappert,

Thermodynamic properties of mixtures

Age related changes in the lipid composition of human lens membranes have been documented and could be responsible for alterations in the function of lens membranes. To establish age related lipid composition-membrane structure relationships, we have examined spectroscopically the hydrocarbon chain structure of lipid membranes from human lens cortex and nucleus 0–95 years of age. Lipid membranes were extracted from human lenses using a monophasic methanolic extraction. The lipid composition of these membranes was determined by 31P-NMR and has already been reported. Fourier transform near-infrared Raman and Fourier transform infrared spectroscopies were used to determine human lens lipid structure. Lipid compositional differences were related to membrane structure. The frequency corresponding to the CH2 symmetric stretching band was found to increase with age in lipid samples from all regions of the lens. The frequency was used to estimate lipid hydrocarbon order. Lipid order was found to increase with age and was not significantly different for lipids extracted from the cortex compared to those from the nucleus. These results were confirmed qualitatively by comparing the height of the 2880 cm−1 band with the height of the 2850 cm−1 Raman band. Increased lipid order with age was also confirmed by the analysis of the C(SINGLE BOND)C stretching bands. Lipid hydrocarbon chain order increased linearly with increasing sphingomyelin content and decreased linearly with increasing phosphatidylcholine content. This trend, similar to that observed in other types of membranes, suggests that these two lipids may play a role in modulating lipid order. © 1996 John Wiley & Sons, Inc.