Reduction of lipid hydroperoxides by apolipoprotein B-100.
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.
Mashima
R
R
Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
Yoshimura
S
S
Yamamoto
Y
Y
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000097:blood*; D001798:Blood Proteins / Q000737:chemistry; D002700:Chloramines / Q000494:pharmacology; D006801:Humans; D008054:Lipid Peroxides / Q000378:metabolism*; D008715:Methionine / Q000031:analogs & derivatives / Q000737:chemistry; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000097:blood / Q000378:metabolism; D014105:Tosyl Compounds / Q000494:pharmacology
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D001798:Blood Proteins; D002700:Chloramines; D008054:Lipid Peroxides; D010713:Phosphatidylcholines; D014105:Tosyl Compounds; C016300:chloramine-T; C057590:phosphatidylcholine hydroperoxide; D008715:Methionine; C013111:methionine sulfoxide