Protective effect of lipoproteins containing apoprotein A‐I on Cu2+ ‐ catalyzed oxidation of human low density lipoprotein

Abstract

Two apoprotein A‐I (apoA‐I)‐containing lipoproteins, one containing apoA‐I and apoA‐II (LpA‐I/A‐II) and the other containing only apoA‐I (LpA‐I), were examined for their effect on Cu²⁺‐mediated oxidation of low density lipoprotein (LDL). The presence of LpA‐I or LpA‐I/A‐II prevented LDL oxidation when assessed by the electrophoretic mobility, apoprotein B fragmentation and amounts of thiobarbituric acid‐reactive substances. The protection of LDL oxidation by these lipoproteins was effective for up to 6 h, with LpA‐I being more active than LpA‐I/A‐II. Results from these in vitro model experiments raise a possibility that LpA‐I mayplay a role in protecting LDL from Cu²⁺ ‐mediated oxidation.