Homocysteine promotes the LDL oxidase activity of ceruloplasmin |
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Authors: | Exner M Hermann M Hofbauer R Hartmann B Kapiotis S Gmeiner B |
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Institution: | Department of Laboratory Medicine, University of Vienna, Vienna, Austria. |
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Abstract: | Ceruloplasmin (CP) oxidises low density lipoprotein (LDL). The oxidising potential depends on the formation of Cu(+)-CP which is redox-cycled during oxidation. Homocysteine (HCY) reduces free Cu(2+), potentiating its cell-damaging property. We show that HCY enhanced LDL oxidation by CP, but did not activate the LDL oxidising potential of Cu(2+)-diamine oxidase. Selective removal of the redox-active Cu(2+) abolished the LDL oxidase activity of CP. However, HCY partially restored the LDL oxidase activity of redox-copper depleted CP, indicating that the remaining six copper atoms in CP may also be involved in the process. Spectroscopic and oxidation inhibition studies using the Cu(+)-reagent bathocuproine revealed that HCY induced Cu(+)-CP formation, thus promoting its LDL oxidase activity. |
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Keywords: | Homocysteine Ceruloplasmin Copper ion LDL oxidation |
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