Direct evidence of caeruloplasmin antioxidant properties |
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Authors: | Atanasiu Roxana L. Stea Dino Mateescu Mircea A. Vergely Catherine Dalloz Florence Briot François Maupoil Véronique Nadeau Réginald Rochette Luc |
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Affiliation: | (1) Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et de Pharmacie, Dijon, France;(2) Departments of Medicine and Physiology and Research Centre, Hôpital du Sacré-Coeur de Montréal, Université de Montréal, Montréal, Québec, Canada;(3) Department of Chemistry, Université du Québec à Montréal, Montréal, Québec, Canada;(4) CEA, Valduc, 21120 Is-sur-Tille, France |
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Abstract: | The chain-breaking antioxidant potential of caeruloplasmin and bovine serum albumin (BSA) has been investigated in comparison with other well-established antioxidants. Their Oxygen Radical Absorbing Capacity (ORAC), was measured by using -phycocyanin (-PC) as a fluorescent indicator protein, 2,2-azobis (2-amidinopropane) hydrochloride (AAPH) as a peroxyl radical generator and the water soluble vitamin E analogue, Trolox, as a reference standard. The relative peroxyl absorbing capacities/mole for Trolox, caeruloplasmin, heat-denatured caeruloplasmin (hCP), catalase, bovine serum albumin (BSA), superoxide dismutase (SOD), and deferoxamine were 1; 2.6; 3.3; 3.7; 1.2; 0.1; 0.2, respectively. Caeruloplasmin was far more effective as a peroxyl radical scavenger than SOD, deferoxamine and BSA, but slightly less effective than catalase. The peroxyl radical absorbing capacity of caeruloplasmin was enhanced by heat-denaturation of the protein. Electron paramagnetic resonance (EPR) spectroscopy using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin-trap, was applied in order to measure the scavenger abilities of caeruloplasmin on superoxide radical and hydroxyl radical production and the concentration required to inhibit by 50% oxygen free radical formation (IC50) was determined. The IC50 values of caeruloplasmin, hCP, and BSA for the superoxide radical were 12, 2, 260 M and for the hydroxyl radical 15, 2, 200 M. These results show that caeruloplasmin is an effective chain-breaking antioxidant for a variety of radicals, independently of its catalytic ferroxidase activity. |
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Keywords: | caeruloplasmin proteins antioxidants electron paramagnetic resonance (EPR) Oxygen Radical Absorbing Capacity (ORAC) |
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