Comparative lipid and heme oxidation of myoglobin, hemoglobin, and cytochrome c in a liposome model

The objective was to compare lipid- and heme-protein oxidation of myoglobin, hemoglobin, and cytochrome c in a phospholipid liposome model. Oxy- and met-forms of myoglobin and hemoglobin, and reduced and oxidized forms of cytochrome c, were incorporated into phosphatidylcholine liposomes and incubated at 37 °C for 4 h. At 4 h of incubation, cytochrome c exhibited lower heme oxidation than oxyhemoglobin and oxymyoglobin. Further, cytochrome c induced the least lipid oxidation at 4 h of incubation compared with myoglobin and hemoglobin (myoglobin > hemoglobin > cytochrome c; P < 0.05). In support, cytochrome c showed lower values for heme release and ferryl intermediate formation (P < 0.05), whereas myoglobin had the highest values for both parameters. The results suggest that cytochrome c's greater structural stability and reduced heme release make it less prone to promoting heme-mediated lipid oxidation than myoglobin and hemoglobin.