Reduction of lipid hydroperoxides by apolipoprotein B-100. |
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Authors: | R Mashima S Yoshimura Y Yamamoto |
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Affiliation: | Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan. |
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Abstract: | ![]() We have previously isolated two proteins which can reduce phosphatidylcholine hydroperoxide (PC-OOH) from human blood plasma and identified one of the proteins as apolipoprotein A-I (Mashima, R. , et al. (1998) J. Lipid Res. 39, 1133-1140). In the present study we have identified the other protein as apolipoprotein B-100 (apo B-100) by amino acid sequence analysis of its tryptic peptides. The reactivity of lipid hydroperoxides with apo B-100 decreased in the order of PC-OOH > linoleic acid hydroperoxide > cholesteryl ester hydroperoxide under our experimental conditions. Pretreatment of apo B-100 with chloramine T, an oxidant of methionine, diminished the PC-OOH-reducing activity, indicating that some of 78 methionines are responsible for the reduction of PC-OOH. Despite the presence of 6 methionines in albumin, albumin was inactive to reduce PC-OOH. Free methionine was also inactive. These data suggest that the accessibility and binding of lipid hydroperoxides to the protein methionine residues are crucial for reduction of lipid hydroperoxides. |
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