Measurement of 5-hydroxy-2-aminovaleric acid as a specific marker of iron-mediated oxidation of proline and arginine side-chain residues of low-density lipoprotein apolipoprotein B-100

An alteration of apolipoprotein (apo) B-100 structure by direct oxidative m odification is supposed to be an important mechanism involved in atherogene sis. There is difficulty in quantifying this type of modification owing to a lack of specific assays. We evaluated a methodology based on the oxidatio n of protein arginine and proline to gamma-glutamyl semialdehyde which by r eduction forms 5-hydroxy-2-aminovaleric acid (HAVA). We determined HAVA by using derivatization to N(O)-ethoxycarbonyl ethyl esters and gas chromatogr aphy-mass spectrometry in different low-density Lipoprotein preparations su bjected to oxidative damage in the presence of iron. Results suggest that a poB-100 proline and arginine residues are highly reactive toward oxygen rad icals ex vivo. Femtomole levels of HAVA can be reproducible measured. HAVA determination compares well with the measurement of carbonyl group formatio n used as a generally accepted but nonspecific index of protein oxidation. Thus, HAVA could prove to be a sensitive assay for studying specific modifi cation of apoB-100. (C) 2000 Academic Press.