Abstract
The ability of ceruloplasmin (Cp) to oxidize low-density lipoproteins (LDL) in the presence of water-soluble antioxidants was investigated and a reaction mechanism proposed. Ascorbate strongly enhanced LDL oxidation, but only after its rapid consumption. Dehydroascorbate enhanced Cp-mediated LDL oxidation even more strongly. Lipid-soluble antioxidants and water-soluble peroxides did not show noticeable activation. However, loading of LDL with lipid hydroperoxides increased the initial oxidation rate. We conclude that Cp mediates a localized redox cycle, where reduction of Cp-Cu2+ is effected by water-soluble reductants and reoxidation by liposoluble hydroperoxides.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Antioxidants / metabolism
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Antioxidants / pharmacology
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Ascorbic Acid / metabolism
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Ascorbic Acid / pharmacology
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Ceruloplasmin / metabolism*
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Copper / metabolism
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Dehydroascorbic Acid / metabolism
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Dehydroascorbic Acid / pharmacology
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Enzyme Activation / drug effects
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Female
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Humans
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Lipid Peroxides / metabolism
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Lipid Peroxides / pharmacology
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Lipoproteins, LDL / metabolism*
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Male
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Oxidation-Reduction / drug effects
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Reducing Agents / metabolism
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Reducing Agents / pharmacology
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Solubility
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Vitamin E / metabolism
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Water / metabolism
Substances
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Antioxidants
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Lipid Peroxides
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Lipoproteins, LDL
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Reducing Agents
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Water
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Vitamin E
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Copper
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Ceruloplasmin
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Ascorbic Acid
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Dehydroascorbic Acid