title: Resonance Raman spectra of beta-carotene in native and modified low-density lipoprotein.
abstract: Low-density lipoproteins isolated between density 1.02 and 1.063 g/cm3 from normal fasting human plasma, show strong resonance Raman spectra due to the presence of beta-carotene. Three intense bands, at 1010, 1160 and 1530 cm-1, are assigned to the stretching vibrations of -C-CH3, = C-C = and -C = C- bonds, respectively, of beta-carotene. High-resolution spectra of the 1500-1600 cm-1 region reveal multiple features, suggesting the coexistence of several structural populations of beta-carotene. The modifications of lipoproteins with pH and temperature (30 degrees-42 degrees) change the resonance Raman spectra of beta-carotene. The specific binding of LDL at pH 7.0 by fibroblast cells is suppressed. Our experiments thus suggest that physical and chemical perturbations of plasma lipoproteins modify the lipid-protein interactions and thereby alter the configurational distribution of beta-carotene molecules within these particles.
mesh_terms: D002338:Carotenoids / Q000032:analysis*; D002460:Cell Line; D005215:Fasting; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000097:blood* / Q000302:isolation & purification / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D011973:Receptors, LDL; D013059:Spectrum Analysis, Raman / Q000379:methods; D013816:Thermodynamics; D019207:beta Carotene
chemical_list: D008077:Lipoproteins, LDL; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; D019207:beta Carotene; D002338:Carotenoids