Hemoglobin induced apolipoprotein B crosslinking in low-density lipoprotein peroxidation

Area of Science:

• Biochemistry
• Cardiovascular Research
• Oxidative Stress

Background:

• Oxidative modification of low-density lipoprotein (LDL) is a key factor in atherosclerosis development.
• Hemoproteins like free hemin, hemoglobin, and myoglobin are implicated as promoters of LDL lipid oxidation.

Purpose of the Study:

• To compare the ability of free hemin and hemoproteins (hemoglobin, myoglobin, horseradish peroxidase) to induce peroxidation modification of apolipoprotein B (apo B).
• To investigate the mechanism of hemoglobin-induced LDL oxidation and the role of antioxidants.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to assess apo B modification.
• Determination of thiobarbituric acid-reactive substances to quantify lipid peroxidation products.
• Assessment of antioxidant inhibition, including Desferal.

Main Results:

• Hemoglobin and myoglobin showed high activity, comparable to free hemin, and significantly greater than horseradish peroxidase (HRP).
• Hemoglobin, myoglobin, and hemin induced apo B aggregation, while HRP caused fragmentation.
• Hemoglobin's reactivity occurred at low H2O2 concentrations and was inhibited by antioxidants.

Conclusions:

• Hemoglobin's high peroxidative reactivity stems from its ability to transfer oxidative equivalents from the heme site through the globin to LDL.
• This process triggers LDL protein and lipid oxidation, contributing to atherosclerosis preconditions.
• Antioxidants inhibit hemoglobin-induced LDL oxidation, suggesting therapeutic potential.