| 研究実績の概要 |
1. Characterization of modifications to pyridoxamine (PM) derived from lipid peroxidation products, 4-oxo-2(E)-nonenal (ONE) and 4-hydroxy-2(E)-nonenal (HNE): LC/ESI-MS analysis of the reaction between PM and ONE/HNE revealed the presence of major adducts PM+ONE-H2O (PO1), PM+ONE-2H2O+2H (PO7), PM+ONE-2H2O (PO8), PM+HNE (PH1) and PM+HNE-2H2O (PH2). PO7 and PH2 have identical LC and MS properties. NMR analysis of the isolated PH2 (PO7) characterized a novel PM adduct containing pyrrole ring that can be derived from both ONE and HNE.
2. Investigation of inhibition effect of PM on ONE/HNE-derived modifications to human serum albumin (HSA): In the incubation of HSA with ONE/HNE, Lys residues provided the most favorable modification sites. When HSA was allowed to react with a linoleic acid hydroperoxide in the presence of ascorbic acid, ONE modified more residues (10 Lys, 3 His, 2 Arg) than did HNE (8 His, 2 Lys), indicating the relative reactivity of aldehydes towards amino acid residues. Upon treatment with increasing concentrations of PM, the levels of all PM-ONE/HNE adducts increased dose-dependently. The MS peak intensities of ONE-modified peptides, but not of HNE-modified peptides, decreased in a PM dose-dependent manner. Our results demonstrate that PM can inhibit lipid hydroperoxide-derived damage to proteins by trapping ONE preferentially.
3. The inhibition effect of PM was also confirmed in the L6 cell system subjected to oxidative stress.
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