Oxidative aggregation of ceruloplasmin induced by hydrogen peroxide is prevented by pyruvate |
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Authors: | Aouffen M'hammed Paquin Joanne Furtos Alexandra Waldron Karen C Mateescu Mircea-Alexandru |
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Institution: | Department of Chemistry and Biochemistry, Université du Québec à Montreal, C.P. 8888, Succ. Centre-ville, Montreal, Qué., Canada H3C 3P8. |
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Abstract: | Ceruloplasmin (CP) is a blue copper glycoprotein with multiple physiological functions including ferroxidase and oxidase activities. CP is also an important serum oxygen free radical (OFR) scavenger and antioxidant, exerting cardioprotective and antifibrillatory actions. Although it has been reported that CP activities can be inhibited by OFR, the intimate mechanism of this inactivation is still not clear. Exposure of bovine CP to H2O2 induced inactivation of the protein as well as structural alterations as indicated by loss of protein bands by SDS-PAGE. Both phenomena were H2O2 concentration and time dependent. HPLC gel filtration and capillary electrophoresis analysis of CP treated with H2O2 revealed an aggregation of the protein. Quantification of dityrosine formation by fluorescence indicated the involvement of dityrosine bridging, which could be responsible for aggregation of CP under oxidative attack. Oxidative damage to CP under H2O2 treatment was completely prevented by pyruvate, suggesting that the association of CP with antioxidants could extend the range of the protective action of this protein. |
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Keywords: | Ceruloplasmin Hydrogen peroxide Metal-catalysed oxidation Aggregation Dityrosine bridges Pyruvate AE: aminoethyl AU: absorbance unit CP: ceruloplasmin CE: capillary electrophoresis DPD: N N-diethyl-p-phenylenediamine EDTA: ethylenediamine tetraacetic acid HPLC: high performance liquid chromatography OFR: oxygen free radicals PDA: -phenylenediamine RFU: relative fluorescence unit SDS-PAGE: sodium dodecylsulfate-polyacrylamide gel electrophoresis |
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