INTERACTION OF HUMAN SERUM LOW DENSITY LIPOPROTEINS WITH PORPHYRINS: A SPECTROSCOPIC AND PHOTOCHEMICAL STUDY |
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| Authors: | J P REYFTMANN P MORLIERE S GOLDSTEIN R SANTUS L DUBERTRET D LAGRANGE |
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| Institution: | 1Laboratoire de Physico-Chimie de l'Adaptation Biologique, CNRS UA 481, Museum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France;Hôpital Henri Mondor, Laboratoire de Recherches Dermatologiques, 94010 Creteil;Laboratoire de Biochimie B, Facultéde Médecine St Antoine, 27 rue de Chaligny, 75012 Paris.;INSERM U 177, Institut Biomédical des Cordeliers, 15–21 rue de I'Ecole de Médecine, 75006 Paris, France |
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| Abstract: | The incorporation of proto-, uro- and hematoporphyrin in low density lipoproteins (LDL) of human blood has been studied by equilibrium dialysis, fluorescence and absorption spectroscopy. The lipoproteins may efficiently compete with albumin in the binding of protoporphyrin to human blood proteins in patients suffering from protoporphyria. It can be concluded that hydrophobic porphyrins bind to blood proteins.
The complexation of hydrophobic porphyrins in LDL is responsible not only for efficient photodynamic effect at the lipoprotein level, but also for photoinduced lipid peroxidation and for consumption of β-carotene incorporated into LDL which are one of their natural carriers. The water-soluble uroporphyrin, although an efficient photosensitizer for the LDL apoprotein photoinactivation, is much less efficient for lipid peroxidation and β-carotene bleaching. The 353 nm laser flash photolysis shows that porphyrin triplet states are not affected by the physiological β-carotene content of LDL but are fully accessible to oxygen. |
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