Mechanism of low-density lipoprotein oxidation by hemoglobin-derived iron.

Excellular hemoglobin is an extremely active oxidant of low-density lipoproteins (LDL), a phenomenon explained so far by different mechanisms. In this study, we analyzed the mechanism of met-hemoglobin oxidability by comparing its mode of operation with other hemoproteins, met-myoglobin and horseradish peroxidase (HRP) or with free hemin. The kinetics of met-hemoglobin activity toward LDL lipids and protein differed from that of met-myoglobin and HRP, both quantitatively and qualitatively.

Oxidation of low-density lipoprotein by hemoglobin-hemichrome.

Hemoglobin and myoglobin are inducers of low-density lipoprotein oxidation in the presence of H(2)O(2). The reaction of these hemoproteins with H(2)O(2) result in a mixture of protein products known as hemichromes. The oxygen-binding hemoproteins function as peroxidases but as compared to classic heme-peroxidases have a much lower activity on small sized and a higher one on large sized substrates.